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General Category => Equipment and Software => Topic started by: gradys on January 20, 2017, 09:50:10 AM

Title: Improved Refractometer Correction calculator
Post by: gradys on January 20, 2017, 09:50:10 AM
Hi,
There are MANY on-line brewing tools and calculators but only one (as far as I know) implements improved method of Refractometer Correction Reading calculation.

It is inspired by work of Petr Novotný (in Czech only: http://diversity-pivo.blogspot.cz/2017/01/pocitame-nova-korekce-refraktometru.html) who dared to challenge famous Sean Terrill formula :)

Results (Hydrometer readings vs Sean Terrill correction vs Petr Novotný correction) can be seen on attached graph. As you can see Improved Formula returns correct values even for fermenting (not only fully fermented) wort.

You can try/test/challenge/discuss/... the new calculator for free on HomeBrewMap site: https://www.homebrewmap.com/en/tools/calculators/refractometer-correction

(http://homebrewmap.com/images/stories/ref_corr_graph.png)
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on January 20, 2017, 12:49:49 PM
Interesting... I signed up (you need to sign up to use the tool) because I noticed discrepancies between refract vs. hydro on my last batch using Sean's calculator, but I'll need quite a bit more data on subsequent batches to determine which tool I prefer.  Thanks for sharing!

One thing the Czech tool does not do is calculate specific gravity, not at all.  To do that, I still end up going back and forth to Sean's calculator.  If that could be added, it would be a more useful tool.

Cheers.
Title: Re: Improved Refractometer Correction calculator
Post by: gradys on January 20, 2017, 01:18:25 PM
Is it better now? Or did you mean something else?

(now it shows corrected value in following format: 7.5 °Plato / 1.030 SG)
Title: Re: Improved Refractometer Correction calculator
Post by: Pricelessbrewing on January 20, 2017, 11:33:51 PM
Saving for later use.

I can't read Czech, how many beers has this been testing with? My experience with refract is that it gets thrown off by some oils as well as ongoing fermentation, grist with high % of oats for example, or highly hopped beers, will cause the refract to deviate more from the hydrometer readings.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on January 21, 2017, 12:23:34 AM
I hate to be captain obvious but why wouldn't you just change the correction factor? Why does their need to be a whole new calculator?

Do you have the source code or the calculations?
Title: Re: Improved Refractometer Correction calculator
Post by: reverseapachemaster on January 21, 2017, 06:14:02 PM
I refuse to think that much about math on a Saturday morning and quite frankly you are an awful person for trying to make me do it.  >:(
Title: Re: Improved Refractometer Correction calculator
Post by: narvin on January 21, 2017, 08:16:30 PM
How does this compare to the "traditional" refractometer calculator that promash, and other software, used to have for calculating the gravity of fermenting wort?  The reason Sean came up with the new formula specifically for final gravity, using empirical data, was because that old equation often underestimated FG.
Title: Re: Improved Refractometer Correction calculator
Post by: a10t2 on January 21, 2017, 08:37:45 PM
Quote
It's probably because his equation wrong, "grafted" to the experimental data. He used merely data for "well-fermented beer", and thus had little and poorly stratified data, which culminated poorly designed coefficients.

No, it's because in the data set I was working with (89 data points from eight breweries - two of them "professional", since that apparently carries some weight), it wasn't possible to generate a mathematically rigorous curve that fit both fermenting wort and gave hydrometer-level precision (±0.05°P) for FG.
Title: Re: Improved Refractometer Correction calculator
Post by: Pricelessbrewing on January 23, 2017, 03:35:39 AM
@a10t2 Who are you quoting there? I don't see that reply anywhere.

I hate to be captain obvious but why wouldn't you just change the correction factor? Why does their need to be a whole new calculator?

Do you have the source code or the calculations?

Wort correction factors vary for every beer, so unless you're measuing the OG with both a refractometer and a hydrometer at reference temperature then you're unlikely to get an accurate WCF. If you are, doesn't that sort of defeat the purpose of it?
Title: Re: Improved Refractometer Correction calculator
Post by: gradys on June 20, 2017, 08:06:55 AM
FYI: you can read a little bit about this "new" approach in latest Zymurgy issue (July/August 2017), article "Revisiting the Refractometer by Petr Novotny".
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on November 23, 2017, 07:28:29 PM
For whatever it's wort...

My own data to date has confirmed the Novotny formula for calculating SG from Brix is a good one.  Not necessarily "better" than Terrill's, but a bit different, and valid in its own right.

And the most accurate FG formula for me is............

None of the above.  :)

Actually, it's the one that Terrill refers to as the "Old Cubic", for which I forget the source but so far it seems closest on the average.  Not perfect either, but close on the average.

To be fair, some of my data is for very high gravity beers, for which no formulae are very accurate -- they are all calculating FG values 0.003-0.006 higher than my hydrometer.  For example there is one beer where my OG was 1.098 as measured by hydrometer (and original Brix was 23.2).  Calculated FG for final Brix 12.9 and correction factor 0.99 (yes, NOT 1.04) was anywhere 1.026-1.029 depending on the formula, but my hydrometer said 1.023.  So, not a big deal -- next time I make a huge beer of OG >1.090, I'll expect to have to subtract a few points from the calculated FG if I skip the hydro and just use refract.  Close enough.

For me, ultimate near-exclusive use of refractometer is desirable, as I am a small batch brewer and would prefer to get 14-15 bottles out of a batch rather than just a 12-pack from too many hydro samples.  For those doing 5 or 10 gallons, sure, I get why you might not care.  But I do.
Title: Re: Improved Refractometer Correction calculator
Post by: Ellismr on November 29, 2017, 11:39:01 AM
(https://uploads.tapatalk-cdn.com/20171129/f63dfe78c5a2bcac63006da8fc24d301.jpg)

I use this application in my iPhone and have checked it against my hydrometer and it was dead on.  Keep in mind I use a digital refractometer. 


Sent from my iPhone using Tapatalk Pro
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 03, 2018, 08:41:16 PM
(https://uploads.tapatalk-cdn.com/20171129/f63dfe78c5a2bcac63006da8fc24d301.jpg)

I use this application in my iPhone and have checked it against my hydrometer and it was dead on.  Keep in mind I use a digital refractometer. 


Sent from my iPhone using Tapatalk Pro
Are you using primelab or terril?
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 04, 2018, 05:31:47 PM
The "Old Cubic" and Novotny formulae continue to be pretty much dead-nuts bulleye for me almost every time, only one odd outlier so far out of five batches.  My own refract vs. hydro data thus far:

(https://farm5.staticflickr.com/4711/25209707127_a6e1827634_b.jpg)

You can hopefully see a very light thin line diagonally from lower left to upper right -- that is the "goal line".  Goal is to be right on that line.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 04, 2018, 05:47:37 PM
The "Old Cubic" and Novotny formulae continue to be pretty much dead-nuts bulleye for me almost every time, only one odd outlier so far out of five batches.  My own refract vs. hydro data thus far:

(https://farm5.staticflickr.com/4711/25209707127_a6e1827634_b.jpg)

You can hopefully see a very light thin line diagonally from lower left to upper right -- that is the "goal line".  Goal is to be right on that line.
I recently broke out my refractometer to check my double mash beer. I think I'm going to be using it more in the mash because I'm going to start trying 45 min or maybe even shorter mashes.

But it got me thinking, can I use it for determining FG. I don't care so much about determining exact FG, so much as Terminal Gravity.

I get lost trying to figure out how to compensate or correct for alcohol. If you don't mind, can you explain it at home brewer user level? And what I would need to do? FYI I have the Brewsor App and Brewers Friend, and an App called Refractometer Calc... Not sure how to use any of them for refractometer correction...

Thanks
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 04, 2018, 06:24:57 PM
Here's what I know based on my experience.  It will seem lengthy, but if you can digest all of it, it should make good sense I believe.

1) First and foremost, you need to check calibration of your refractometer with every single use.  That's right -- EVERY use.  The readings on a refractometer really seem to bounce around a lot each time I use mine.  First measure plain distilled water and ensure it reads exactly zero.  If it doesn't, you can either adjust the screw in the thing (I haven't even done this) or else figure out about how far off it is from zero, then add or subtract that number of points when reading wort.  For example, mine often seems to read about negative-0.2 Brix with plain water.  So then I dry the thing off, then add a few drops of wort and add +0.2 Brix for an accurate reading.  If you don't check calibration every time and adjust from zero, then the readings are pretty much useless and you're wasting your time.  The next time you use the thing, even just 5 minutes later, check it with water again, because it probably moved!  Readings are not stable, that's been my experience, so I calibrate every single time I'm going to use it.  Even check it with water again immediately after measuring wort, and if the readings aren't the same in water each time, take the average of how far off it is from zero and apply that.  So, for example again, if I check in plain water again and now it reads exactly 0.0 Brix, but I got negative-0.2 Brix before, figure I should add the average +0.1 Brix to the reading in wort instead of +0.2.  This will provide the utmost accuracy.  The more measurements and experience you gain, the more accurate your readings will be.

2) You must use both your refractometer (recording your readings IN BRIX) and hydrometer together many times with OG readings (zero ABV) along with ANY refract-to-hydro calculator (it does NOT matter which one) such as Sean Terrill's (http://seanterrill.com/2012/01/06/refractometer-calculator/) or Petr Novotny's (see info in the OP above) so that you can learn the "correction factor" for your specific refractometer.  Every refractometer is a little different in this respect.  Sean Terrill suggests an average correction factor of 1.04 for many refractometers his cohorts have tested.  However, do NOT assume your refractometer's correction factor is 1.04 without testing it out.  Mine definitely has a correction factor of exactly 0.99.  I have learned this after measuring the OG of at least 11 batches, and now that I know this correction factor, the results are always extremely consistent and predictable.

3) Okay.... so now let's say you know your correction factor.  You've measured several OGs of several different worts, and it's matching up perfectly with your hydrometer reading every single time.  Okay.  Now you're ready to use it for FG readings!  Until this point, your FG readings will be a crapshoot!  But now that you know how to use the thing and apply the proper correction factor, you can use it for FG.  Yay.  So to do that........ I personally recommend either Petr Novotny's formulae available from the OP, or use the "Old Cubic" formula which very ironically is available in Excel spreadsheet format from Mr. Sean Terrill at: http://seanterrill.com/wp-content/uploads/2011/04/fg_calculator_v3.0.xls 
Check calibration of your refractometer in water as before, then measure your final wort in BRIX, then pump that into Terrill's spreadsheet but use the result from the column that says "Old Cubic".  That will give you the results you see in the chart above as red squares -- almost dead-nuts accuracy.  The one goofy data point above, by the way, was where my OG was like 1.098.  None of the refractometer calculators are very accurate with high gravity worts of greater than about 1.080 or 1.085.  They'll still work okay for high gravity, but in my experience you'll probably need to subtract 0.003 or so to match a hydrometer reading.

Note: Hydrometer readings will ALWAYS have the greatest accuracy.  Refractometers with good calculators can get you very very close indeed to a hydro reading, within 0.001-0.002, but only that accurate if you follow appropriate standard scientific practice as I've attempted to provide in all the guidance above.

I certainly hope this helps somebody more than it causes confusion.  It's working really awesome for me, with my small batches (average 2 gallons).  I have a lot of confidence now when using refractometers for FG and ABV that I am getting very accurate results consistent with the more reliable hydrometer readings.  So now I don't need to waste a big hydro sample.  Just a few drops and I'm good to go.

Cheers.
Title: Re: Improved Refractometer Correction calculator
Post by: denny on February 04, 2018, 06:26:03 PM
After reading the post above, it's confirmed my decision to stick with a hydrometer.
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 04, 2018, 06:33:50 PM
After reading the post above, it's confirmed my decision to stick with a hydrometer.

It's really not complicated.  Calibration and knowing your correction factor are the keys.  Once you've got those two things down, you're golden.  Makes more sense to do for small batch brewers too.  Love my refractometer.  I actually find it a little faster and easier to use, too.
Title: Re: Improved Refractometer Correction calculator
Post by: denny on February 04, 2018, 06:35:15 PM
After reading the post above, it's confirmed my decision to stick with a hydrometer.

It's really not complicated.  Calibration and knowing your correction factor are the keys.  Once you've got those two things down, you're golden.  Makes more sense to do for small batch brewers too.

And I have to do none of that with a hydrometer.  I can get a hydrometer reading about as quickly as a refractometer reading, especially including all the calibration.  I don't see any reason to not use a hydrometer.
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 04, 2018, 06:40:08 PM
After reading the post above, it's confirmed my decision to stick with a hydrometer.

It's really not complicated.  Calibration and knowing your correction factor are the keys.  Once you've got those two things down, you're golden.  Makes more sense to do for small batch brewers too.

And I have to do none of that with a hydrometer.  I can get a hydrometer reading about as quickly as a refractometer reading, especially including all the calibration.  I don't see any reason to not use a hydrometer.

It's just another thing to nerd out about.  Like IBUs and SRMs and LODO and pH and water and........ we are all friggin nerds in this hobby to some extent -- ain't we!?!?
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 04, 2018, 06:54:50 PM
After reading the post above, it's confirmed my decision to stick with a hydrometer.

Me too, not even absolutely sure where my refractometer is!  But this thread leads me to a related question.  I've noticed some people use a refractometer to determine when their mash has gone to completion. I rely on an iodine test.  What am I missing?
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 04, 2018, 06:57:57 PM
After reading the post above, it's confirmed my decision to stick with a hydrometer.

Me too, not even absolutely sure where my refractometer is!  But this thread leads me to a related question.  I've noticed some people use a refractometer to determine when their mash has gone to completion. I rely on an iodine test.  What am I missing?

You check gravity after mash rests to see how close you are getting to the target gravity. For instance, I use no-sparge and step mash, so I use Kai’s maximum first wort gravity prediction and refractometer readings to determine my conversion efficiency.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 04, 2018, 07:00:37 PM
After reading the post above, it's confirmed my decision to stick with a hydrometer.

Me too, not even absolutely sure where my refractometer is!  But this thread leads me to a related question.  I've noticed some people use a refractometer to determine when their mash has gone to completion. I rely on an iodine test.  What am I missing?

You check gravity after mash rests to see how close you are getting to the target gravity. For instance, I use no-sparge and step mash, so I use Kai’s maximum first wort gravity prediction and refractometer readings to determine my conversion efficiency.
So since I sparge, no real advantage to my using a refractometer,  right?
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 04, 2018, 07:02:52 PM
this thread leads me to a related question.  I've noticed some people use a refractometer to determine when their mash has gone to completion. I rely on an iodine test.  What am I missing?

Iodine test will tell you when much, but not all, of the starches are converted to sugars.  But results will vary and are not very reliable.  On the other hand, measuring gravity or Brix over time will tell you if conversion is still going on.  If more sugars are being produced, readings will continue to rise.  Only when readings stay stable over the course of ~10 minutes is conversion really "done".  And even then, it might only be telling you about conversion of starches into sugars, but not whether those sugars are very fermentable!  So even then, you might for certain styles want to mash even longer!

Ultimately, at a certain point, you need to make a decision and just stop mashing when you think it's been "good enough".  For me, I mash for only 45 minutes usually, but am starting to mash longer for some styles.  I don't even measure pre-boil.  I get good efficiency pretty consistently so I just keep on rocking.  The whole thing is all optional, and decisions can be based on personal experience where appropriate, and we might not need to measure every dang thing like many of us tend to do.  Even FG....... does it really matter????  If the final beer tastes good, who cares about the FG!!  Or the ABV!!  Does it really matter????  It's a decision we each need to make on our own.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 04, 2018, 07:08:20 PM
After reading the post above, it's confirmed my decision to stick with a hydrometer.

Me too, not even absolutely sure where my refractometer is!  But this thread leads me to a related question.  I've noticed some people use a refractometer to determine when their mash has gone to completion. I rely on an iodine test.  What am I missing?

You check gravity after mash rests to see how close you are getting to the target gravity. For instance, I use no-sparge and step mash, so I use Kai’s maximum first wort gravity prediction and refractometer readings to determine my conversion efficiency.
So since I sparge, no real advantage to my using a refractometer,  right?

Wrong. You can still calculate the maximum first wort gravity using Kai’s formulas and determine the efficiency of conversion. It just works out good when you no-sparge because the first wort gravity IS your preboil gravity.

It has nothing to do with a refractometer. I just happen to use a refractometer instead of a hydrometer.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 04, 2018, 07:10:15 PM
I mash 60, just because, iodine test to make sure everything's going as usual, mash off 10-20 and sparge.  I get good yield (>33ppg in homebrew terms) and good attenuation (>78% ADF).  I'll stick with that. :)
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 04, 2018, 07:12:36 PM
I mash 60, just because, iodine test to make sure everything's going as usual, mash off 10-20 and sparge.  I get good yield (>33ppg in homebrew terms) and good attenuation (>78% ADF).  I'll stick with that. :)

Whatever floats your boat. We are into knowing all the particulars of a batch so that we can improve and strengthen our spreadsheet so we get more in depth than most. Nothing wrong with doing what works.
Title: Re: Improved Refractometer Correction calculator
Post by: denny on February 04, 2018, 07:39:24 PM
I mash 60, just because, iodine test to make sure everything's going as usual, mash off 10-20 and sparge.  I get good yield (>33ppg in homebrew terms) and good attenuation (>78% ADF).  I'll stick with that. :)

I've found the iodine test unreliable, so I use conversion efficiency to make sure the mash is done.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 04, 2018, 07:49:10 PM
1. Calibrate with H2O every use. Already do that, check

2. Compare hydrometer to refractometer several times with unfermented wort to confirm MY correction factor.

3. Use the calculator with MY correction factor, or be crazy and skip step 2 and just use 1.04 lol

Thanks! I will do step 2 for a while and learn my correction factor. How many batches do you think? And could I do this by creating several various samples of sugar water?

Meanwhile I will use the calculator with 1.04 but compare my results to hydrometer FG and calculated ABV.

PS, sorry I started a fight
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 04, 2018, 07:53:52 PM
1. Calibrate with H2O every use. Already do that, check

2. Compare hydrometer to refractometer several times with unfermented wort to confirm MY correction factor.

3. Use the calculator with MY correction factor, or be crazy and skip step 2 and just use 1.04 lol

Thanks! I will do step 2 for a while and learn my correction factor. How many batches do you think? And could I do this by creating several various samples of sugar water?

Meanwhile I will use the calculator with 1.04 but compare my results to hydrometer FG and calculated ABV.

PS, sorry I started a fight

I would calculate the correction factor for your equipment and run with it. Especially for just checking pre-fermentation wort.

You may want to be a little more rigorous for measuring fermenting wort but even then, I’ve never found it necessary to recalculate the correction factor unless you see something amiss in your numbers.

I firmly believe in Dave’s assertion before that the correction factor specific to you is key in getting reliable numbers out of your unit.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 04, 2018, 07:58:22 PM
I mash 60, just because, iodine test to make sure everything's going as usual, mash off 10-20 and sparge.  I get good yield (>33ppg in homebrew terms) and good attenuation (>78% ADF).  I'll stick with that. :)

I've found the iodine test unreliable, so I use conversion efficiency to make sure the mash is done.

Time was, I checked the mash with a refractometer at the same time as my iodine test.  I quit because it was one more thing to do, and it was always exactly the same.  I just looked at Kai's table and guess what?  There's the number I was always hitting.  So I guess I've sort of calibrated my system, and as long as I'm using similar malts and water/grain ratios, I probably don't even need the iodine test (it's always negative by 60 min anyway) but it's a habit.  If I ever decide to make radical changes, now I know how to dial it in again! Thanks all.
Title: Re: Improved Refractometer Correction calculator
Post by: denny on February 04, 2018, 08:41:10 PM
I mash 60, just because, iodine test to make sure everything's going as usual, mash off 10-20 and sparge.  I get good yield (>33ppg in homebrew terms) and good attenuation (>78% ADF).  I'll stick with that. :)

I've found the iodine test unreliable, so I use conversion efficiency to make sure the mash is done.

Time was, I checked the mash with a refractometer at the same time as my iodine test.  I quit because it was one more thing to do, and it was always exactly the same.  I just looked at Kai's table and guess what?  There's the number I was always hitting.  So I guess I've sort of calibrated my system, and as long as I'm using similar malts and water/grain ratios, I probably don't even need the iodine test (it's always negative by 60 min anyway) but it's a habit.  If I ever decide to make radical changes, now I know how to dial it in again! Thanks all.

Excellent, man!  The key is always to find what works for YOU!
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 04, 2018, 08:47:31 PM
Looks like I'm going to blind trust 1.04, because my smart phone doesn't play well with excel
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 04, 2018, 09:15:47 PM
Looks like I'm going to blind trust 1.04, because my smart phone doesn't play well with excel

Don’t do it!

The Excel app doesn’t work for you?
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 04, 2018, 09:49:48 PM
Looks like I'm going to blind trust 1.04, because my smart phone doesn't play well with excel
Jim, what kind of phone? What's it doing?
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 04, 2018, 09:49:50 PM
Looks like I'm going to blind trust 1.04, because my smart phone doesn't play well with excel

Don’t do it!

The Excel app doesn’t work for you?
Nope. I downloaded it, and can see it, but it won't even let me enter data.

So, what is the worst that can happen if I arbitrarily used the correction factor of 1.04?
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 04, 2018, 09:54:16 PM
Looks like I'm going to blind trust 1.04, because my smart phone doesn't play well with excel

Don’t do it!

The Excel app doesn’t work for you?
Nope. I downloaded it, and can see it, but it won't even let me enter data.

So, what is the worst that can happen if I arbitrarily used the correction factor of 1.04?

It MAY skew your numbers. Then again, 1.04 might be your number.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 04, 2018, 09:55:11 PM
Quote from: klickitat jim pink=topic=28544.msg404397#msg404397 date=1517777251
Looks like I'm going to blind trust 1.04, because my smart phone doesn't play well with excel

Don’t do it!

The Excel app doesn’t work for you?
Nope. I downloaded it, and can see it, but it won't even let me enter data.


Jim, if it says your file is read only, you just have to save a copy.  You should be able to save changes to that copy.  (I save each recipe I do in Bru'n Water with the recipe in th e file name.)  Otherwise it's just a matter of getting your finger on those tiny little fields!
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 04, 2018, 09:58:25 PM
Just playing around with my refractometer app, using 20° OG and 10° FG I get the following ABVs by changing the correction factor to...

1.08 7.2%
1.04 7.5%
1.00 7.8%
.98 7.8%

Frankly that's totally close enough for me! My main use of FG readings is to verify Terminal Gravity. When people ask me what the ABV of my beers is, I usually ask "what does it seem like?" Their perception is more valuable to me than what it actually is. Then I'll tell them a rounded off figure, like if it's calculated to 7.35% I'll say "it's about 7%".

Will using an arbitrary correction factor cause my refractometer final gravity readings to bounce around, so long as I use the same factor?
Title: Re: Improved Refractometer Correction calculator
Post by: denny on February 04, 2018, 10:00:53 PM


So, what is the worst that can happen if I arbitrarily used the correction factor of 1.04?

The end of civilization as we know it!   ;D
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 04, 2018, 10:02:52 PM


So, what is the worst that can happen if I arbitrarily used the correction factor of 1.04?

The end of civilization as we know it!   ;D
Right! Just have to define what end of civilization means, lol. Off by 1/2 A percent ABV is totally liveable and civilized enough for me
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 04, 2018, 10:06:11 PM


So, what is the worst that can happen if I arbitrarily used the correction factor of 1.04?

The end of civilization as we know it!   ;D
Right! Just have to define what end of civilization means, lol. Off by 1/2 A percent ABV is totally liveable and civilized enough for me

We care more about being precise for Spunding and knowing when to transfer the beer.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 04, 2018, 10:10:01 PM


So, what is the worst that can happen if I arbitrarily used the correction factor of 1.04?

The end of civilization as we know it!   ;D
Right! Just have to define what end of civilization means, lol. Off by 1/2 A percent ABV is totally liveable and civilized enough for me

We care more about being precise for Spunding and knowing when to transfer the beer.
Does that answer my question? Not being sarcastic, just wondering if I'm having a stroke or something
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 04, 2018, 10:39:00 PM


So, what is the worst that can happen if I arbitrarily used the correction factor of 1.04?

The end of civilization as we know it!   ;D
Right! Just have to define what end of civilization means, lol. Off by 1/2 A percent ABV is totally liveable and civilized enough for me

We care more about being precise for Spunding and knowing when to transfer the beer.
Does that answer my question? Not being sarcastic, just wondering if I'm having a stroke or something

I was just responding to your “off by 1/2 % ABV” statement. If that what you are concerned with, then who cares if you just SWAG the correction factor. OTOH, if you are trying to get accurate FFT readings, fermentation readings, or precise readings for determine transfer gravities, then it’s important to actually measure the correction factor.

If you mean this question:

Looks like I'm going to blind trust 1.04, because my smart phone doesn't play well with excel

Don’t do it!

The Excel app doesn’t work for you?
Nope. I downloaded it, and can see it, but it won't even let me enter data.

So, what is the worst that can happen if I arbitrarily used the correction factor of 1.04?

It MAY skew your numbers. Then again, 1.04 might be your number.

I answered it already.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 04, 2018, 10:40:54 PM
Disregard: I found one that works in brewers friend! I'll do about 5 test each  in about 5 different worts and see what my correction factor actually is.

I'm going to do this tonight with dme/water. I'll do 10%, 15%, 20%, and 25%.

Huge thanks do dmtaylor for typing up that thorough explanation!

Big thanks to Monk for johnny on the spotting me.

And thanks Denny for keeping it fun
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 04, 2018, 11:02:31 PM
You guys think dme will dissolve in room temp water? I might break out my stir plate for this project
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 04, 2018, 11:09:23 PM
You guys think dme will dissolve in room temp water? I might break out my stir plate for this project
Jim, I liked this idea and I don't care about the super bowl hype I'll miss.  I just made up some samples with BOILING water and stuck them in the fridge to chill to room temp.  Never thought to try with cool water, but hot works.

If I do decide to use the old refracto again, I'll know my number! Thanks for the idea.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 04, 2018, 11:23:11 PM
You betcha. I'll try dme in room temp on the stir plate and see what happens. Actually, i have a bunch of precanned 1.040 to start with. Record my findings, add more... etc etc. I don't think it needs to take 6 months of brew days to figure this out.

Something fun to do that should end up with easier results. Maybe even more reliable results, given that we're learning that hydrometer in suspended solids is inaccurate
Title: Re: Improved Refractometer Correction calculator
Post by: BrewnWKopperKat on February 05, 2018, 12:17:12 AM
You guys think dme will dissolve in room temp water? I might break out my stir plate for this project

While I've never tried dissolving DME in cold water, this 
http://blog.brewingwithbriess.com/kiss-those-dme-clumps-goodbye-2/
suggests your approach will work. 
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 05, 2018, 12:20:35 AM
You guys think dme will dissolve in room temp water? I might break out my stir plate for this project

While I've never tried dissolving DME in cold water, this 
http://blog.brewingwithbriess.com/kiss-those-dme-clumps-goodbye-2/
suggests your approach will work.
Hilarious! Thanks
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 05, 2018, 12:20:43 AM
You guys think dme will dissolve in room temp water? I might break out my stir plate for this project
Jim, I liked this idea and I don't care about the super bowl hype I'll miss.  I just made up some samples with BOILING water and stuck them in the fridge to chill to room temp.  Never thought to try with cool water, but hot works.

If I do decide to use the old refracto again, I'll know my number! Thanks for the idea.

Well, my samples (3) were all over the place, correction factor ranging from 0.93 to 0.98.  I'm just going to keep on not using the refractometer,  I don't trust it. Part of why I quit using it.  I'll rely on my longtime experience that tells me my mashing procedure is solid!  But hey, it was fun to give this a try.  Hope you have better luck, Jim, I know you kinda dig that refractometer!
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 05, 2018, 12:26:01 AM
You guys think dme will dissolve in room temp water? I might break out my stir plate for this project

While I've never tried dissolving DME in cold water, this 
http://blog.brewingwithbriess.com/kiss-those-dme-clumps-goodbye-2/
suggests your approach will work.
Made my day! 😂
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 05, 2018, 12:32:04 AM
You guys think dme will dissolve in room temp water? I might break out my stir plate for this project

While I've never tried dissolving DME in cold water, this 
http://blog.brewingwithbriess.com/kiss-those-dme-clumps-goodbye-2/
suggests your approach will work.
Made my day!
Reinheitsgebort-bort-bort
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 05, 2018, 12:36:39 AM
So I'm thinking. Long ago when I got my refractometer it was reliable.  Then at some point it seemed to become anything but (this little test confirms that's still the case) so I just stashed and forgot it. Wonder if anyone knows of them just going bad?  (It is a <$100 model.)
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 05, 2018, 12:41:17 AM
Seems to me the simple ones are totally mechanical, like a pair of binoculars. Maybe something got knocked loose. But my most likely suspect is that your solution was not totally homogenous. Big volume with hydrometer in it, measuring gravity of the whole volume... Then tiny variable sample on the refractometer.

Hence why I'll be doing mine on a stir plate. 10 min stir, measure, add , 10 min stir etc

Did you recalibrate before each sample?
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 05, 2018, 12:53:51 AM
Seems to me the simple ones are totally mechanical, like a pair of binoculars. Maybe something got knocked loose. But my most likely suspect is that your solution was not totally homogenous. Big volume with hydrometer in it, measuring gravity of the whole volume... Then tiny variable sample on the refractometer.
Either is possible.  It got farther off the higher the gravity, and mechanical misalignment could do that, or the lack of homogeneity would be more of a factor as gravity went up.  But I did try to avoid just that kind of problem with the samples, and if the cheapies are all mechanical,  I'll bet on jiggly bits inside the thing. Don't really need it, won't bother with it again. 

Good lesson for anybody thinking of buying one -- you get what you pay for!

 And hydrometers and iodine are dead simple.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 05, 2018, 12:54:14 AM
So I'm thinking. Long ago when I got my refractometer it was reliable.  Then at some point it seemed to become anything but (this little test confirms that's still the case) so I just stashed and forgot it. Wonder if anyone knows of them just going bad?  (It is a <$100 model.)

Not sure but mine cost all of $15 and is bang on every time.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 05, 2018, 12:57:59 AM
Mine is Chinese cheaply too
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 05, 2018, 01:06:59 AM
Mine may have been ok at some point then, but it did definitely start wildly disagreeing with my hydrometer all of a sudden years ago. If I ever replace it I guess I won't worry about price, though I've heard  cheap ones derided by those with $3000 or whatever bench models.  Of course they have to rationalize their investment!
Title: Re: Improved Refractometer Correction calculator
Post by: tommymorris on February 05, 2018, 01:37:52 AM
After reading the post above, it's confirmed my decision to stick with a hydrometer.
I applaud you for actually reading it.
Title: Re: Improved Refractometer Correction calculator
Post by: tommymorris on February 05, 2018, 01:44:17 AM
FWIW, I love my hydrometer and use it for OG and FG. I generally don’t know how accurate it is. Ball park is close enough for me.

I did check it against my hydrometer today. The Refractometer + BeerSmith calculator matched a hydrometer for the FG of a batch of blonde ale.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 05, 2018, 03:11:11 AM
Numbers
Cleaned and calibrated every sample
All hydrometer numbers corrected to temp
1.020 3x always 4.6°      .91
1.028 3x always 7.4°    1.04
1.050 3x always 13.4°  1.08
1.067 3x always 16.6°  1.01
1.088 3x always 21°       .99
1.102 3x always 25°     1.03
My correction factor is 1.012

Proved to me that my refractometer is always steady, and much easier to read a precise number. If I get different readings from a single wort, it's not homogenous!

I will be putting this to the test, with a few hydrometer checks to see how close I get.

Good stuff! Thanks again guys!
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 05, 2018, 03:18:00 AM
Numbers
Cleaned and calibrated every sample
All hydrometer numbers corrected to temp
1.020 3x always 4.6°      .91
1.028 3x always 7.4°    1.04
1.050 3x always 13.4°  1.08
1.067 3x always 16.6°  1.01
1.088 3x always 21°       .99
1.102 3x always 25°     1.03
My correction factor is 1.012

Proved to me that my refractometer is always steady, and much easier to read a precise number. If I get different readings from a single wort, it's not homogenous!

I will be putting this to the test, with a few hydrometer checks to see how close I get.

Good stuff! Thanks again guys!
Jim, you mean your AVERAGE wort correction is 1.012, right?  I was getting consistent results AT EACH gravity, it just varied so wildly between gravities.  I don't think I could just average the correction, I'd have to make a table of corrections at every possible gravity.  This seems absurdly untenable, unless I'm really missing something?
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 05, 2018, 03:28:18 AM
It's all done by the excell sheet, so I don't know. But it's 3 separate but identical readings at each gravity. The correction factor is the same at each gravity. Different at different gravities, I don't claim to know why, but that IS why it takes readings at different gravities to come up with the average. I'm not at all freaked out about it because it works, according to people far smarter than me. Sean Terril, if I recall correctly, is a nuke tech.

Trust, but verify. I'll try it out and compare with hydrometer samples.

FYI, I did 3 years at each gravity because brewers friend suggested 5... 3 is more than 1... 5 seemed too much, especially since they were all the same.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 05, 2018, 03:48:33 AM
It's all done by the excell sheet, so I don't know. But it's 3 separate but identical readings at each gravity. The correction factor is the same at each gravity. Different at different gravities, I don't claim to know why, but that IS why it takes readings at different gravities to come up with the average. I'm not at all freaked out about it because it works, according to people far smarter than me. Sean Terril, if I recall correctly, is a nuke tech.

Trust, but verify. I'll try it out and compare with hydrometer samples.
Exactly,  trust but verify.  The problem I have is the verify part looks like a PITA, and I'd have to have that because it just doesn't look right to my smaller-than-Terril's brain that the factor should jump all over like that... think I'm back where I started.  Hydrometer don't lie.   :D
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 05, 2018, 03:52:51 AM
^^^^
Just realized: spreadsheet? Your Excel problem is solved, then?

And which spreadsheet are you using?  The one in Brewer's Friend that wants 30 samples?!
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 05, 2018, 04:24:54 AM
Brewers Friend one worked for me. Sean's wouldn't cooperate and as I looked at it, it wasn't the one for determining correction factor.
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 05, 2018, 12:03:06 PM
I don't think the correction factor should be jumping around by that much.  When I was determining my factor, it ranged from about 0.94-0.99 but never so far out of whack to be in the 1.0's or 0.8's.  With experience I determined I needed to zero the gauge with water more often because readings would creep.  So I measure water both before AND after reading the wort.  Did you do that?  It could explain the degree of bounciness you were seeing in the factor.  Try to get the range tighter before declaring "1.012".

Also in science there is something known as an anomylous result or outlier, which is a result so odd that it is thrown out.  The 0.91 in your results appears wildly anomylous and should probably be tossed out if you cannot duplicate it.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 05, 2018, 12:36:46 PM
^^^^
For me at least, yes, calibrated and had to make  no adjustments.  Water steady, wort bouncy.   Hydrometer trusty.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 05, 2018, 01:37:00 PM


I don't think the correction factor should be jumping around by that much.  When I was determining my factor, it ranged from about 0.94-0.99 but never so far out of whack to be in the 1.0's or 0.8's.  With experience I determined I needed to zero the gauge with water more often because readings would creep.  So I measure water both before AND after reading the wort.  Did you do that?  It could explain the degree of bounciness you were seeing in the factor.  Try to get the range tighter before declaring "1.012".

Also in science there is something known as an anomylous result or outlier, which is a result so odd that it is thrown out.  The 0.91 in your results appears wildly anomylous and should probably be tossed out if you cannot duplicate it.

Cleaned and calibrated before each sample, which means after as well... remove the outliers and it's 1.02

The variance is not my refractometer, it's the interpretation of where the interface is on the hydrometer.

I also think it's much ado about nothing. The difference of correction between the ouyliers in a high gravity wort where the most change would show... If I stick with what I got, a 20BrixWRI reading is corrected to 19.8°/1.083 If I remove the outliers it's 19.6/1.082. In a normal gravity beer 15BrixWRI swings wildly from 14.8°/1.061 to 14.7°/1.061....

I'm happy with what I've learned and my results. Thanks again
Title: Re: Improved Refractometer Correction calculator
Post by: Phil_M on February 05, 2018, 01:53:04 PM
So I'm thinking. Long ago when I got my refractometer it was reliable.  Then at some point it seemed to become anything but (this little test confirms that's still the case) so I just stashed and forgot it. Wonder if anyone knows of them just going bad?  (It is a <$100 model.)

I don't know about others, but I've noticed that when measuring hot wort evaporation plays a HUGE part in the final reading. If this was about FG readings, then disregard.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 05, 2018, 01:55:49 PM
So I'm thinking. Long ago when I got my refractometer it was reliable.  Then at some point it seemed to become anything but (this little test confirms that's still the case) so I just stashed and forgot it. Wonder if anyone knows of them just going bad?  (It is a <$100 model.)

I don't know about others, but I've noticed that when measuring hot wort evaporation plays a HUGE part in the final reading. If this was about FG readings, then disregard.

I usually cool the samples by inverting the dropping and putting the bulb in a container of chilled water. Doesnt take long and gives me more consistent results. Also, the quality of the sample (bubbles, clarity, etc.) plays a role too.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 05, 2018, 01:55:58 PM
So I'm thinking. Long ago when I got my refractometer it was reliable.  Then at some point it seemed to become anything but (this little test confirms that's still the case) so I just stashed and forgot it. Wonder if anyone knows of them just going bad?  (It is a <$100 model.)

I don't know about others, but I've noticed that when measuring hot wort evaporation plays a HUGE part in the final reading. If this was about FG readings, then disregard.
I'd expect that to consistently cause error on the high side, which is not happening here. 
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 05, 2018, 02:23:55 PM
What prompted me to pursue this was learning that suspended solids (yeast, hop matter, proteins etc) can render a hydrometer to be inaccurate by as much as 10 gravity points. That's no bueno. So how to confirm it's accurate? These solids don't effect refractometer accuracy, sooooo here I am. Plus less is needed for a reading. Plus it's much easier to see where the line is, at least for my eyes. Just explaining why I'm doing this, not trying to change anyone.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 05, 2018, 02:26:40 PM
Plus less is needed for a reading.

This was a biggie for me. I'm only putting 1.25 gallons into the fermenter and I don't recycle gravity samples so a hydrometer is a no-go for me.
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 05, 2018, 02:28:08 PM
What prompted me to pursue this was learning that suspended solids (yeast, hop matter, proteins etc) can render a hydrometer to be inaccurate by as much as 10 gravity points. That's no bueno. So how to confirm it's accurate? These solids don't effect refractometer accuracy, sooooo here I am. Plus less is needed for a reading. Plus it's much easier to see where the line is, at least for my eyes. Just explaining why I'm doing this, not trying to change anyone.

It can be dang near impossible to get a good reading on a refractometer if the beer is hazy.  For that I might actually resort to my trusty old hydro!  I have a hard time believing a hydro could be off by more than 2 points, much less 10 points.  It'd have to be a pretty mucky brew to have that kind of effect, wow.
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 05, 2018, 02:28:53 PM
Plus less is needed for a reading.

This was a biggie for me. I'm only putting 1.25 gallons into the fermenter and I don't recycle gravity samples so a hydrometer is a no-go for me.

Wow... I can see your schwarz is even smaller than mine!
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 05, 2018, 02:31:46 PM
Plus less is needed for a reading.

This was a biggie for me. I'm only putting 1.25 gallons into the fermenter and I don't recycle gravity samples so a hydrometer is a no-go for me.

Wow... I can see your schwarz is even smaller than mine!

It's the only way I can brew. 2 kids under 5, full-time job, and no dedicated brew space? I rely on short heat up and cool down times to even be able to brew. Also, I don't drink much, at least in a relative sense. 5-6 bottles a week.

Even with all that said, it's still tough to get more than one session per month in.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 05, 2018, 02:34:47 PM
I've been digging through textbooks trying to find any reference to use of anything but iodine test to confirm complete conversion (this was where I thought refracto might be in order.) Nada.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 05, 2018, 02:43:54 PM
I've been digging through textbooks trying to find any reference to use of anything but iodine test to confirm complete conversion (this was where I thought refracto might be in order.) Nada.

I mean, you don't really need a textbook to tell you there are other ways to determine conversion:

1.) You know your target gravity;

2.) There are resources (1) that show an approximate level of beta activity per step, so you know to look for a percentage of your extract after each mash step;

3.) If at the end of a mash you are getting significantly less extract than predicted (with losses, etc. factored in), you know your conversion was incomplete.

We've used the multi-step Brauwelt mash shown below on many occasions and have been able to reliably predict conversion through careful analysis of gravity at each step.

(1) Brauwelt International – Some reflections on mashing –  Part 1: http://www.lowoxygenbrewing.com/wp-content/uploads/2017/04/pkjdf.pdf (http://www.lowoxygenbrewing.com/wp-content/uploads/2017/04/pkjdf.pdf) and Part 2: http://www.lowoxygenbrewing.com/wp-content/uploads/2017/04/pddvxvf.pdf (http://www.lowoxygenbrewing.com/wp-content/uploads/2017/04/pddvxvf.pdf)

At the end of the day though, what you are doing is working for you, and if it gives you the level of information that you require, then why change it?
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 05, 2018, 02:48:24 PM
^^^^
Yep. Enough years of consistent RESULTS, if it ain't broke don't fix it.  There's a difference between a lab and a brewhouse.

EDIT I also keep forgetting that this is different for those of you doing no sparge, you have to know when the converted material has leached into the liquid.  As I'm doing a conventional sparge, that happens during said sparge, so I just need to know when saccharification is complete.  Iodine does that.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 05, 2018, 03:05:02 PM
^^^^
Yep. Enough years of consistent RESULTS, if it ain't broke don't fix it.  There's a difference between a lab and a brewhouse.

EDIT I also keep forgetting that this is different for those of you doing no sparge, you have to know when the converted material has leached into the liquid.  As I'm doing a conventional sparge, that happens during said sparge, so I just need to know when saccharification is complete.  Iodine does that.

Right. We calculate target first wort gravity (maximum) based on Kai's equations, and the base our ACTUAL estimates of that. Actuals will depending on conversion and our losses.
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 05, 2018, 03:19:58 PM
It's the only way I can brew. 2 kids under 5, full-time job, and no dedicated brew space? I rely on short heat up and cool down times to even be able to brew. Also, I don't drink much, at least in a relative sense. 5-6 bottles a week.

Even with all that said, it's still tough to get more than one session per month in.

We digress, but I can relate.  I only have about 2 beers per week on average.  My 3 kids are a little older now but not by much -- 14, 13, and 10.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 07, 2018, 10:28:32 PM
Update: I am so impressed with the repeatability of my refractometer that I changed all of my recipes to °p
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 07, 2018, 10:45:51 PM
Update: I am so impressed with the repeatability of my refractometer that I changed all of my recipes to °p

Yours reads °P or °Bx?
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 07, 2018, 10:58:40 PM
Mine reads BrixWRI. That's one reason you do the correction factor, or so I'm told. Then you have °P I believe. And °P and the Spauling scale are the same until you get out about the 4th decimal

Anyway... I'll be looking at BrixWRI, converting to °P and comparing to my recipe.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 07, 2018, 11:02:05 PM
Would look like this in the end(https://uploads.tapatalk-cdn.com/20180207/6426f9576adb0eca83bb7ec9fce0273d.jpg)
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 07, 2018, 11:03:43 PM
Mine reads BrixWRI. That's one reason you do the correction factor, or so I'm told. Then you have °P I believe. And °P and the Spauling scale are the same until you get out about the 4th decimal

Anyway... I'll be looking at BrixWRI, converting to °P and comparing to my recipe.

The correction factor is the conversion from RI to °Bx if I’m not mistaken. °Bx to °P is close enough to 1.04 for the gravities we have that I SWAG with that.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 07, 2018, 11:06:04 PM
I also believe it's needed for Kai's chart, since the column is labeled Plato. Entirely possible that folks who don't know their correction factor and compute displayed Brix to °P are not getting what they think they are getting

With my $17 refractometer, if it reads 10brix the corrected °P would be 9.9 so WAAAAAYYYYY off
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 07, 2018, 11:48:37 PM
I also believe it's needed for Kai's chart, since the column is labeled Plato. Entirely possible that folks who don't know their correction factor and compute displayed Brix to °P are not getting what they think they are getting

With my $17 refractometer, if it reads 10brix the corrected °P would be 9.9 so WAAAAAYYYYY off

I need to look at our spreadsheet. I made some changes today and I think I need to switch back. I think the correction IS the °Bx to °P conversion. I changed it today thinking I was wrong and now I think I was right.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 07, 2018, 11:53:31 PM
Here's what I'm going by
"How to Determine your Refractometer’s Wort Correction Factor

When taking a refractometer measurement of wort, the Brix reading is not necessarily accurate. What is obtained is the Brix WRI (wort refraction index).  Only after dividing the Brix WRI by the wort correction factor is the actual Brix known. It is helpful to know that Brix and Plato are nominally the same to 3 decimal places, so the corrected reading can be treated as Plato (°P).

The correction factor is needed because wort has a different density than sugar water which refractometers are designed for.  The wort correction factor is specific to the instrument."

From a Brewers Friend article explaining their correction factor spreadsheet

By the way, don't think that I did a bunch of work changing my recipes from SG to °P, it's just a click of a button, lol

Title: Re: Improved Refractometer Correction calculator
Post by: coolman26 on February 08, 2018, 12:12:42 AM
I just read all 10 pages. It is confirmed that this forum is going nowhere.
Excellent read by the way. I always use both hydro and refract. I’ve always calibrated and used. Learn something here every visit.


Sent from my iPhone using Tapatalk
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 08, 2018, 12:21:53 AM
Here's what I'm going by
"How to Determine your Refractometer’s Wort Correction Factor

When taking a refractometer measurement of wort, the Brix reading is not necessarily accurate. What is obtained is the Brix WRI (wort refraction index).  Only after dividing the Brix WRI by the wort correction factor is the actual Brix known. It is helpful to know that Brix and Plato are nominally the same to 3 decimal places, so the corrected reading can be treated as Plato (°P).

The correction factor is needed because wort has a different density than sugar water which refractometers are designed for.  The wort correction factor is specific to the instrument."

From a Brewers Friend article explaining their correction factor spreadsheet

By the way, don't think that I did a bunch of work changing my recipes from SG to °P, it's just a click of a button, lol

The problem I have is in reading Kai’s conversion chart, you see that an additional factor of 1.04 (across a range of 1.048-1.100 S.G.) needs to be applied to convert °Bx to °P. Unless I’m fouling up concepts here:

1.) Refractometer correction factor takes you from RI to °Bx;

2.) Using Kai’s chart, there exists an additional 1.04 factor across common gravities to concert °Bx to °P.

Maybe I’m wrong? That’s how I’ve always handled it in the LOB spreadsheet, but this conversation has me rethinking myself.

EDIT: On second look, Kai’s Table is labeled, “Refractometer °Bx reading to °P” so it’s liking just conversion factor values, so no extra multiplier needed.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 08, 2018, 12:35:58 AM
Here's what I'm going by
"How to Determine your Refractometer’s Wort Correction Factor

When taking a refractometer measurement of wort, the Brix reading is not necessarily accurate. What is obtained is the Brix WRI (wort refraction index).  Only after dividing the Brix WRI by the wort correction factor is the actual Brix known. It is helpful to know that Brix and Plato are nominally the same to 3 decimal places, so the corrected reading can be treated as Plato (°P).

The correction factor is needed because wort has a different density than sugar water which refractometers are designed for.  The wort correction factor is specific to the instrument."

From a Brewers Friend article explaining their correction factor spreadsheet

By the way, don't think that I did a bunch of work changing my recipes from SG to °P, it's just a click of a button, lol

The problem I have is in reading Kai’s conversion chart, you see that an additional factor of 1.04 (across a range of 1.048-1.100 S.G.) needs to be applied to convert °Bx to °P. Unless I’m fouling up concepts here:

1.) Refractometer correction factor takes you from RI to °Bx;

2.) Using Kai’s chart, there exists an additional 1.04 factor across common gravities to concert °Bx to °P.

Maybe I’m wrong? That’s how I’ve always handled it in the LOB spreadsheet, but this conversation has me rethinking myself.

EDIT: On second look, Kai’s Table is labeled, “Refractometer °Bx reading to °P” so it’s liking just conversion factor values, so no extra multiplier needed.
So Kai took the leap of faith that we would all need to use Sean's correction factor of 1.04?  How was he not pummeled for That?

Again, it's small taters. Pick a method and go with it, I say. Frankly my eyes aren't good enough to see .1 brix WRI. Best I can do is count the .2 marks
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 08, 2018, 12:38:08 AM
All I know is the 1.04 correction factor does NOT work perfectly for my refractometer.... but a factor of 0.99 does.

Does it really matter?  Now there's a question with no perfect answer!
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 08, 2018, 12:45:02 AM
Does it really matter?  Now there's a question with no perfect answer!

Why this forum isn't going away. 8)
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 08, 2018, 12:49:59 AM
Here's what I'm going by
"How to Determine your Refractometer’s Wort Correction Factor

When taking a refractometer measurement of wort, the Brix reading is not necessarily accurate. What is obtained is the Brix WRI (wort refraction index).  Only after dividing the Brix WRI by the wort correction factor is the actual Brix known. It is helpful to know that Brix and Plato are nominally the same to 3 decimal places, so the corrected reading can be treated as Plato (°P).

The correction factor is needed because wort has a different density than sugar water which refractometers are designed for.  The wort correction factor is specific to the instrument."

From a Brewers Friend article explaining their correction factor spreadsheet

By the way, don't think that I did a bunch of work changing my recipes from SG to °P, it's just a click of a button, lol

The problem I have is in reading Kai’s conversion chart, you see that an additional factor of 1.04 (across a range of 1.048-1.100 S.G.) needs to be applied to convert °Bx to °P. Unless I’m fouling up concepts here:

1.) Refractometer correction factor takes you from RI to °Bx;

2.) Using Kai’s chart, there exists an additional 1.04 factor across common gravities to concert °Bx to °P.

Maybe I’m wrong? That’s how I’ve always handled it in the LOB spreadsheet, but this conversation has me rethinking myself.

EDIT: On second look, Kai’s Table is labeled, “Refractometer °Bx reading to °P” so it’s liking just conversion factor values, so no extra multiplier needed.
Big, I was looking at the page in Kai's blog about the conversion chart. I can't find where he says it's pre-corrected to 1.04
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 08, 2018, 12:51:27 AM
All I know is the 1.04 correction factor does NOT work perfectly for my refractometer.... but a factor of 0.99 does.

Does it really matter?  Now there's a question with no perfect answer!
Right. 1.04 would be a WAG. Your own calculated correction factor would improve your accuracy to SWAG
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 08, 2018, 12:51:41 AM
We have Refractometer stuff integrated into our sheet so I just like to make sure I keep it as accurate as possible.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 08, 2018, 12:58:14 AM
Here's what I'm going by
"How to Determine your Refractometer’s Wort Correction Factor

When taking a refractometer measurement of wort, the Brix reading is not necessarily accurate. What is obtained is the Brix WRI (wort refraction index).  Only after dividing the Brix WRI by the wort correction factor is the actual Brix known. It is helpful to know that Brix and Plato are nominally the same to 3 decimal places, so the corrected reading can be treated as Plato (°P).

The correction factor is needed because wort has a different density than sugar water which refractometers are designed for.  The wort correction factor is specific to the instrument."

From a Brewers Friend article explaining their correction factor spreadsheet

By the way, don't think that I did a bunch of work changing my recipes from SG to °P, it's just a click of a button, lol

The problem I have is in reading Kai’s conversion chart, you see that an additional factor of 1.04 (across a range of 1.048-1.100 S.G.) needs to be applied to convert °Bx to °P. Unless I’m fouling up concepts here:

1.) Refractometer correction factor takes you from RI to °Bx;

2.) Using Kai’s chart, there exists an additional 1.04 factor across common gravities to concert °Bx to °P.

Maybe I’m wrong? That’s how I’ve always handled it in the LOB spreadsheet, but this conversation has me rethinking myself.

EDIT: On second look, Kai’s Table is labeled, “Refractometer °Bx reading to °P” so it’s liking just conversion factor values, so no extra multiplier needed.
Big, I was looking at the page in Kai's blog about the conversion chart. I can't find where he says it's pre-corrected to 1.04

http://braukaiser.com/documents/Kaiser_Brix_Plato_SG_table.pdf

It says “Refractometer °Bx to Wort °P” so my assumption is:

1.) Refractometer °Bx = BrixWRI;
2.) Wort °P = Wort °Bx

You can crunch the numbers and see that for a range of 1.048-1.100 the conversion is ~1.04.

I think this conversation gave me what I need to square my calcs away.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 08, 2018, 01:01:47 AM
Here's what I'm going by
"How to Determine your Refractometer’s Wort Correction Factor

When taking a refractometer measurement of wort, the Brix reading is not necessarily accurate. What is obtained is the Brix WRI (wort refraction index).  Only after dividing the Brix WRI by the wort correction factor is the actual Brix known. It is helpful to know that Brix and Plato are nominally the same to 3 decimal places, so the corrected reading can be treated as Plato (°P).

The correction factor is needed because wort has a different density than sugar water which refractometers are designed for.  The wort correction factor is specific to the instrument."

From a Brewers Friend article explaining their correction factor spreadsheet

By the way, don't think that I did a bunch of work changing my recipes from SG to °P, it's just a click of a button, lol

The problem I have is in reading Kai’s conversion chart, you see that an additional factor of 1.04 (across a range of 1.048-1.100 S.G.) needs to be applied to convert °Bx to °P. Unless I’m fouling up concepts here:

1.) Refractometer correction factor takes you from RI to °Bx;

2.) Using Kai’s chart, there exists an additional 1.04 factor across common gravities to concert °Bx to °P.

Maybe I’m wrong? That’s how I’ve always handled it in the LOB spreadsheet, but this conversation has me rethinking myself.

EDIT: On second look, Kai’s Table is labeled, “Refractometer °Bx reading to °P” so it’s liking just conversion factor values, so no extra multiplier needed.
Big, I was looking at the page in Kai's blog about the conversion chart. I can't find where he says it's pre-corrected to 1.04

http://braukaiser.com/documents/Kaiser_Brix_Plato_SG_table.pdf

It says “Refractometer °Bx to Wort °P” so my assumption is:

1.) Refractometer °Bx = BrixWRI;
2.) Wort °P = Wort °Bx

You can crunch the numbers and see that for a range of 1.048-1.100 the conversion is ~1.04.

I think this conversation gave me what I need to square my calcs away.
Ok. I thought you were talking about...(https://uploads.tapatalk-cdn.com/20180208/a733f8cbf6123a1c4110a9fdddd31a2f.gif)
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 08, 2018, 01:08:58 AM
Guys, I'm confused now.  I did those disconcerting experiments trying to determine the correction factor for my particular instrument, you recall. I think I'm still leaning toward sticking with my hydrometer, but: am I now to understand that I didn't have to do that? Is 1.04 in fact not a WAG but a reliable universal correction on any instrument calibrated to 0?
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 08, 2018, 01:10:50 AM
Guys, I'm confused now.  I did those disconcerting experiments trying to determine the correction factor for my particular instrument, you recall. I think I'm still leaning toward sticking with my hydrometer, but: am I now to understand that I didn't have to do that? Is 1.04 in fact not a WAG but a reliable universal correction on any instrument calibrated to 0?

I'm a bit confused too, but, I'm pretty sure each individual instrument has its own quirks such that I plan to continue to use 0.99 for my correction factor even if it's "wrong" cuz I'm sure it's right, for me.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 08, 2018, 01:12:07 AM
Here's what I'm going by
"How to Determine your Refractometer’s Wort Correction Factor

When taking a refractometer measurement of wort, the Brix reading is not necessarily accurate. What is obtained is the Brix WRI (wort refraction index).  Only after dividing the Brix WRI by the wort correction factor is the actual Brix known. It is helpful to know that Brix and Plato are nominally the same to 3 decimal places, so the corrected reading can be treated as Plato (°P).

The correction factor is needed because wort has a different density than sugar water which refractometers are designed for.  The wort correction factor is specific to the instrument."

From a Brewers Friend article explaining their correction factor spreadsheet

By the way, don't think that I did a bunch of work changing my recipes from SG to °P, it's just a click of a button, lol

The problem I have is in reading Kai’s conversion chart, you see that an additional factor of 1.04 (across a range of 1.048-1.100 S.G.) needs to be applied to convert °Bx to °P. Unless I’m fouling up concepts here:

1.) Refractometer correction factor takes you from RI to °Bx;

2.) Using Kai’s chart, there exists an additional 1.04 factor across common gravities to concert °Bx to °P.

Maybe I’m wrong? That’s how I’ve always handled it in the LOB spreadsheet, but this conversation has me rethinking myself.

EDIT: On second look, Kai’s Table is labeled, “Refractometer °Bx reading to °P” so it’s liking just conversion factor values, so no extra multiplier needed.
Big, I was looking at the page in Kai's blog about the conversion chart. I can't find where he says it's pre-corrected to 1.04

http://braukaiser.com/documents/Kaiser_Brix_Plato_SG_table.pdf

It says “Refractometer °Bx to Wort °P” so my assumption is:

1.) Refractometer °Bx = BrixWRI;
2.) Wort °P = Wort °Bx

You can crunch the numbers and see that for a range of 1.048-1.100 the conversion is ~1.04.

I think this conversation gave me what I need to square my calcs away.
Ok. I thought you were talking about...(https://uploads.tapatalk-cdn.com/20180208/a733f8cbf6123a1c4110a9fdddd31a2f.gif)

Nope that’s his maximum first wort gravity chart, which is our gravity estimation engine in our spreadsheet. We like Kai! 😁
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 08, 2018, 01:14:51 AM
Guys, I'm confused now.  I did those disconcerting experiments trying to determine the correction factor for my particular instrument, you recall. I think I'm still leaning toward sticking with my hydrometer, but: am I now to understand that I didn't have to do that? Is 1.04 in fact not a WAG but a reliable universal correction on any instrument calibrated to 0?

I'm a bit confused too, but, I'm pretty sure each individual instrument has its own quirks such that I plan to continue to use 0.99 for my correction factor even if it's "wrong" cuz I'm sure it's right, for me.

No. You guys are right. There is a different correction factor for everyone. 1.04 is a generally accepted default value but empirical data says it varies wildly. What I was trying to say, and what is now erroneous, is that I thought an additional factor needed to be applied to convert from Wort °Bx to Wort °P. Not the case.

You guys are on point. Everyone’s correction factor is different. I wouldn’t be surprised if ST just used Kai’s as the default.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 08, 2018, 01:16:32 AM
My hydrometer doesnt make my head hurt like this.  But nothing makes my head hurt like something that seems like it should be straightforward, but you just can't find a clear answer in all the information out there! Or even whether sources are using terms consistently.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 08, 2018, 01:19:48 AM
My hydrometer doesnt make my head hurt like this.  But nothing makes my head hurt like something that seems like it should be straightforward, but you just can't find a clear answer in all the information out there! Or even whether sources are using terms consistently.

It’s really simple: determine your units correction factor and you are good to go.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 08, 2018, 01:22:01 AM
What's more, there is going to be a different correction factor for each gravity. That's why we do so many test samples, to determine the average correction factor.

The end result difference between a 1.04 and 1.02 is quite minimal. Nothing to get in a twist about.

If you recall, I was cautioned about using my outliers. Well the difference in the final results between with outliers or without is like 1/2 of a gravity point in a moderate beer
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 08, 2018, 01:27:17 AM
That was the problem.  My tests were all over the place (consistent w/in gravity, erratic between gravities)  so I don't see a factor for my unit I can trust.  I can't get my head around why an average would be valid when the apparent correction did not skew along a smooth curve or line as gravity increased:  just bounced around.  So I couldn't call anything an outlier, there was just no pattern.

EDIT And how, anyway, could I trust that a given reading on a given brew day was not itself an outlier?
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 08, 2018, 01:41:42 AM
Here is the way we do it and why I feel, empirically that it works:

1.) We calculate a “target” first wort gravity using Kai’s idealized equation, i.e. 100% Mash Efficiency, 80% DBFG, and 4% moisture. This gives you the maximum theoretically possible first wort gravity. Since we assume no-sparge this is the maximum theoretical pre-boil gravity.

2.) We then calculate the “estimated” first wort gravity by subbing actual malt parameters and mash efficiency into Kai’s equation. We know that this will deviate from the “target” as mash tun Losses and absorption increases and converge with the “target” with less loss and smaller grain bills. 

3.) We use a static value for Refractometer correction and always measure very close to our estimates, so it must be nothing if not consistent.

One caveat though: We (the royal We as in many of us at LOB forum) are in a pretty tight gravity range. Even me, who only brews Trappist “style” ales, stay pretty moderate on wort gravity and supplement with sugar.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 08, 2018, 01:44:25 AM
That was the problem.  My tests were all over the place (consistent w/in gravity, erratic between gravities)  so I don't see a factor for my unit I can trust.  I can't get my head around why an average would be valid when the apparent correction did not skew along a smooth curve or line as gravity increased:  just bounced around.  So I couldn't call anything an outlier, there was just no pattern.

EDIT And how, anyway, could I trust that a given reading on a given brew day was not itself an outlier?
Near as I can figure, my variations are largely due to my ability to read the hydrometer. I suspect that if I used an easier to read precision hydrometer the swing would tighten. To me it's fine. I can't tell, by looking at my hydrometer in wort, the difference between 1.060 and 1.0605... I also have no way of knowing if suspended solids are effecting the hydrometer. So there is still a degree of trust involved if all you use is a hydrometer.

All good folks. I don't sell refractometers, lol
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 08, 2018, 01:52:44 AM
I guess I'll stick with my hydro (again as I sparge, I use iodine to confirm conversion in the tun anyway), but over time I may occasionally take a refracto reading on occasion and see if it's consistent in normal wort range. Just for fun, if I can remember. I have a hydro that even my crappy old eyes can read the 0.0005 lines on (actually 3 narrow range hydrometers), and I don't use it on mash, only wort, so floaties aren't a factor.  And I don't sell hydrometers either!
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 08, 2018, 08:02:42 PM
UPDATE AND APOLOGY FOR QUESTIONING  YOU GUYS' METHODS

So I had some time today.  Thought about some methodology you guys suggested.  Got out the stir plate, used Jim's method, and did a MUCH more extensive series of tests.  I also remembered that Jim thought that a lack of homogeneity might show up big time in the refractometer sample, so I took those readings FIRST right out of the beaker on the stir plate and THEN checked with the hydrometer.  Well! 

Result:  very consistent for the most part, and even the apparent outliers, when included in an average of all tests, fall precisely in line with the result excluding them.  I get a correction factor of 0.97, which, having gone through this, I accept.  I will now trust the refractometer enough for on-the-fly assessment of wort in the mash and boil.  But I'm still sticking with my precision hydrometers for OG and beyond.

Big Monk, Jim, guys, thanks for helping me get my head around this! 
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 08, 2018, 08:15:26 PM
There ya go. Cool
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 08, 2018, 08:19:21 PM
Another test i want to do is hydrometer in distilled water at calibrated temp, compared to the same water with a obviously visible amout of yeast in suspension. Palmer claims starch is suspension threw his off by 10 points. I hope to not ever have visibly starch in mine, but occasionally there's visible yeast.
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 08, 2018, 08:20:45 PM
I'd be very very interested to hear anyone's results for FG using the refractometer, once they know their correction factor.  Use the "Old Cubic" or the OP's calculator, and watch just how close you come.  You may find as I have that the refractometer is every bit as useful for FG as it is for OG.

Cheers all.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 08, 2018, 08:31:28 PM
Another test i want to do is hydrometer in distilled water at calibrated temp, compared to the same water with a obviously visible amout of yeast in suspension. Palmer claims starch is suspension threw his off by 10 points. I hope to not ever have visibly starch in mine, but occasionally there's visible yeast.
10 points sounds like a lot, but I know mine often has dropped (apparently) about 1 point pre- to post- cold crash.  I never know whether that's a change in suspended yeast, or just in bubbles lifting the hydrometer,or the temperature fudge factor. I guess at that point there's not a huge amount of yeast still in suspension anyway.  Either way, I just assume the accurate FG is the post crash.  (In fact I don't even do the pre crash anymore, but that's to avoid opening the carboy now that I'm hyper  cold side O2 conscious!  In fact I don't see a need for any gravity readings but OG and FG taken after the fact.  And the only reason for that is, if attenuation was off, I'd reculture instead of repitching. I know my yeast.) Anywho, if you do the experiment I'll be curious to see the post!
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 08, 2018, 08:32:44 PM
I'd be very very interested to hear anyone's results for FG using the refractometer, once they know their correction factor.  Use the "Old Cubic" or the OP's calculator, and watch just how close you come.  You may find as I have that the refractometer is every bit as useful for FG as it is for OG.

Cheers all.

I have the "New Cubic" and "New Linear" calculations coded into our spreadsheet on a toggle. "New Cubic"is the one I've gotten the best results from. "Old Cubic" always seems low to me.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 08, 2018, 08:41:49 PM
I'd be very very interested to hear anyone's results for FG using the refractometer, once they know their correction factor.  Use the "Old Cubic" or the OP's calculator, and watch just how close you come.  You may find as I have that the refractometer is every bit as useful for FG as it is for OG.

Cheers all.
I just signed up to use the OP's calculator.  I'll report here!
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 08, 2018, 08:51:30 PM
I'd be very very interested to hear anyone's results for FG using the refractometer, once they know their correction factor.  Use the "Old Cubic" or the OP's calculator, and watch just how close you come.  You may find as I have that the refractometer is every bit as useful for FG as it is for OG.

Cheers all.
I just signed up to use the OP's calculator.  I'll report here!

...And we're officially back on-topic!  ;D  8)
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 08, 2018, 08:52:52 PM
I'd be very very interested to hear anyone's results for FG using the refractometer, once they know their correction factor.  Use the "Old Cubic" or the OP's calculator, and watch just how close you come.  You may find as I have that the refractometer is every bit as useful for FG as it is for OG.

Cheers all.

I have the "New Cubic" and "New Linear" calculations coded into our spreadsheet on a toggle. "New Cubic"is the one I've gotten the best results from. "Old Cubic" always seems low to me.

Try the OP's calculator.  I think you'll be impressed.

EDIT: FYI, I add a constant 0.001 to every result when using the Old Cubic.  A little tweak like that can make a real difference in our judgment of it.  The curvature is not affected, just the vertical placement on the graph.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 08, 2018, 11:48:25 PM
I'd be very very interested to hear anyone's results for FG using the refractometer, once they know their correction factor.  Use the "Old Cubic" or the OP's calculator, and watch just how close you come.  You may find as I have that the refractometer is every bit as useful for FG as it is for OG.

Cheers all.
I just signed up to use the OP's calculator.  I'll report here!

And now that I've finally read the Novotný article in _Zymurgy_ (reply #9) I don't even feel like busting out the hydrometers to cross check the refractometer, the evidence behind the calculations looks solid.  I might just go all-in on the refracto.  I much prefer working in Plato anyway (right, Jim?)  I love how just about every brew cycle the forum has me getting out of some rut I was stuck in and making some unexpected improvement!
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 09, 2018, 12:15:32 AM
I'd be very very interested to hear anyone's results for FG using the refractometer, once they know their correction factor.  Use the "Old Cubic" or the OP's calculator, and watch just how close you come.  You may find as I have that the refractometer is every bit as useful for FG as it is for OG.

Cheers all.

I have the "New Cubic" and "New Linear" calculations coded into our spreadsheet on a toggle. "New Cubic"is the one I've gotten the best results from. "Old Cubic" always seems low to me.

Try the OP's calculator.  I think you'll be impressed.

Why is that? Just the high level overview if you don’t mind. I’m curious.

I’ve had such good luck with Sean’s calculator.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 09, 2018, 12:26:34 AM
I'd be very very interested to hear anyone's results for FG using the refractometer, once they know their correction factor.  Use the "Old Cubic" or the OP's calculator, and watch just how close you come.  You may find as I have that the refractometer is every bit as useful for FG as it is for OG.

Cheers all.

I have the "New Cubic" and "New Linear" calculations coded into our spreadsheet on a toggle. "New Cubic"is the one I've gotten the best results from. "Old Cubic" always seems low to me.

Try the OP's calculator.  I think you'll be impressed.

Why is that? Just the high level overview if you don’t mind. I’m curious.

I’ve had such good luck with Sean’s calculator.
Big Monk, have a look at the Novotný article, Jul/Aug 2017 _Zymurgy_  (and the graph in the original post.)  OP's calc allows use of Novotný equation, which tracks hydro closer than Terill, and he also has really good empirical data behind the calculations it includes for fermenting and fermented beer.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 09, 2018, 12:34:42 AM
I'd be very very interested to hear anyone's results for FG using the refractometer, once they know their correction factor.  Use the "Old Cubic" or the OP's calculator, and watch just how close you come.  You may find as I have that the refractometer is every bit as useful for FG as it is for OG.

Cheers all.

I have the "New Cubic" and "New Linear" calculations coded into our spreadsheet on a toggle. "New Cubic"is the one I've gotten the best results from. "Old Cubic" always seems low to me.

Try the OP's calculator.  I think you'll be impressed.

Why is that? Just the high level overview if you don’t mind. I’m curious.

I’ve had such good luck with Sean’s calculator.
Big Monk, have a look at the Novotný article, Jul/Aug 2017 _Zymurgy_  (and the graph in the original post.)  OP's calc allows use of Novotný equation, which tracks hydro closer than Terill, and he also has really good empirical data behind the calculations it includes for fermenting and fermented beer.

I’m good with that, I’m just curious about Dave’s statement where he says it tracks the “Old Cubic” from ST’s calculator. Plugging in some data and expanding ST’s sheet to include columns for apparent Attenuation for the “Old Cubic” column shows me getting unrealistic amounts of Attenuation.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 09, 2018, 12:46:17 AM
^^^^
I don't know from "old cubic."  But looking at the article and the evidence presented, like I said above, I'm ready to shelve the hydros and use the OP's calculator.  You will understand the material better than I, but the article references foundational research you might even be able to incorporate on your own.  He just did the actual tests to confirm the corrections for fermenting/fermented beer.  Now I don't have to, and I suspect Dave has already tested it out himself and doesn't need me to!

To use the calculator you just have to register with their website, a Prague-based homebrew group.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 09, 2018, 12:58:38 AM
^^^^
I don't know from "old cubic."  But looking at the article and the evidence presented, like I said above, I'm ready to shelve the hydros and use the OP's calculator.  You will understand the material better than I, but the article references foundational research you might even be able to incorporate on your own.  He just did the actual tests to confirm the corrections for fermenting/fermented beer.  Now I don't have to, and I suspect Dave has already tested it out himself and doesn't need me to!

To use the calculator you just have to register with their website, a Prague-based homebrew group.

I registered earlier today and ran some brewery numbers from about 10 WY3787 batches and the OP calc had my attenuation outside the realm of reality. I’m going to locate the article and give it a read to make sure I’m not missing anything.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 09, 2018, 01:27:54 AM
I have only ONE data point to offer at this point:  the beer I have on tap right now.  I stole a drop or two and put it through the OP's calc.  The Terill result is indeed closer to my notes than the Novotný,  both are a little lower.  But my notes are of a hydro reading of beer from the lagering tank, with some suspended yeast and upwelling of CO2, so I'm inclined to trust either of the refracto numbers over my hydro as noted, they are right in the expected range of attenuation (78-80% with 34/70) whereas I wondered why I was only showing 76%.  Which to trust more?  I'll wait for somebody smarter to chime in.  They both look highly plausible, and FG is far less critical than mash and boil data.  Either should be close enough for judging time for a diacetyl rest.  Awaiting further information.  I'm going to go drink the rest of this glass of Pils, thank you. 8)
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 09, 2018, 01:31:20 AM
I have only ONE data point to offer at this point:  the beer I have on tap right now.  I stole a drop or two and put it through the OP's calc.  The Terill result is indeed closer to my notes than the Novotný,  both are a little lower.  But my notes are of a hydro reading of beer from the lagering tank, with some suspended yeast and upwelling of CO2, so I'm inclined to trust either of the refracto numbers over my hydro as noted, they are right in the expected range of attenuation (78-80% with 34/70) whereas I wondered why I was only showing 76%.  Which to trust more?  I'll wait for somebody smarter to chime in.  They both look highly plausible, and FG is far less critical than mash and boil data.  Either should be close enough for judging time for a diacetyl rest.  Awaiting further information.  I'm going to go drink the rest of this glass of Pils, thank you. 8)

I’m trying to get my hands on the zymurgy article so I can look at the write up. Then I’ll take some notes over the next few batches.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 09, 2018, 01:52:09 AM
^^^^
Let me guess, you're not an AHA member? If you are it's easy to access from the main site.  And as an aside, remember the kerfuffle over that keg purging disinformation?  Well it's nice to see the level of material being published with Gordon Strong as technical editor!
Title: Re: Improved Refractometer Correction calculator
Post by: Richard on February 09, 2018, 04:07:12 AM
I read the Zymurgy article, and there is an equation listed in it. I put that into my spreadsheet right next to Terril's old cubic that I had been using. For my current batch, the Novotny formula gave values about 2 points higher down to a gravity of 1.032, then 1 point higher below that. At the end of fermentation the ST formula gives 1.008, the Novotny formula gives 1.009 and my hydrometer gives 1.009. I would say that these are all so close to each other that it is hard to really say that one is better than the other. I need lots more brews to be sure, not that I needed any extra motivation to brew.
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 09, 2018, 04:50:13 AM
I'd be very very interested to hear anyone's results for FG using the refractometer, once they know their correction factor.  Use the "Old Cubic" or the OP's calculator, and watch just how close you come.  You may find as I have that the refractometer is every bit as useful for FG as it is for OG.

I have the "New Cubic" and "New Linear" calculations coded into our spreadsheet on a toggle. "New Cubic"is the one I've gotten the best results from. "Old Cubic" always seems low to me.

Try the OP's calculator.  I think you'll be impressed.

Why is that? Just the high level overview if you don’t mind. I’m curious.

I’ve had such good luck with Sean’s calculator.

See earlier post:

https://www.homebrewersassociation.org/forum/index.php?topic=28544.msg404356#msg404356

Terrill's research was only for "well fermented beer".  Novotny's works very accurately at ANY point during fermentation... and more accurate at FG in my experience as well.

Old Cubic is almost just as accurate in my own experience.  YMMV.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 09, 2018, 05:17:10 AM
Thanks Dave.  That helps me line up a few mental data points.  I have for reasons irrelevant here taken my last hydro reading differently in the last few batches.   Novotný, if correct,  would in this instance confirm I've had no actual change in attenuation.  Score one for refracto.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 09, 2018, 12:33:37 PM
I'd be very very interested to hear anyone's results for FG using the refractometer, once they know their correction factor.  Use the "Old Cubic" or the OP's calculator, and watch just how close you come.  You may find as I have that the refractometer is every bit as useful for FG as it is for OG.

I have the "New Cubic" and "New Linear" calculations coded into our spreadsheet on a toggle. "New Cubic"is the one I've gotten the best results from. "Old Cubic" always seems low to me.

Try the OP's calculator.  I think you'll be impressed.

Why is that? Just the high level overview if you don’t mind. I’m curious.

I’ve had such good luck with Sean’s calculator.

See earlier post:

https://www.homebrewersassociation.org/forum/index.php?topic=28544.msg404356#msg404356

Terrill's research was only for "well fermented beer".  Novotny's works very accurately at ANY point during fermentation... and more accurate at FG in my experience as well.

Old Cubic is almost just as accurate in my own experience.  YMMV.

Awesome. I put together a modified ST sheet for tracking and Bryan and I are going to take some notes over the course of 20 or so batches.
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 09, 2018, 01:22:26 PM
I placed this EDIT above, but here it is again because it matters:

FYI, I add a constant 0.001 to every result when using the Old Cubic.  A little tweak like that can make a real difference in our judgment of it.  The curvature is not affected, just the vertical placement on the graph.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 09, 2018, 01:44:01 PM
I placed this EDIT above, but here it is again because it matters:

FYI, I add a constant 0.001 to every result when using the Old Cubic.  A little tweak like that can make a real difference in our judgment of it.  The curvature is not affected, just the vertical placement on the graph.

My observation, when taking into consideration that I am interested only in final gravity and last 4 points preceding it (for accurately transferring beer with extract to packaging), is that most of the graphs converge at or near final gravity. The issue with that then is that if the Old Cubic and Novotny equations estimate a lower FG with a constant input (Original Bx), it would jive with some of the numbers I have now, i.e. unrealistic attenuation based on empirical findings.

I'll have to track this over some batches and see what happens.
Title: Re: Improved Refractometer Correction calculator
Post by: gradys on February 09, 2018, 04:15:56 PM
^^^^
Just realized: spreadsheet? Your Excel problem is solved, then?

And which spreadsheet are you using?  The one in Brewer's Friend that wants 30 samples?!

FYI: You can also determine Refractometer Correction Factor online here: https://www.homebrewmap.com/en/tools/calculators/refractometer-correction-factor
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 09, 2018, 06:39:12 PM
Yeast suspension effect posted in a new thread under general topics
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 14, 2018, 09:08:02 PM
Trusting Novotný enough that I'm doing current batch without bothering with hydrometers.  Just checked mid fermentation, and OP's calculator with Novotný shows gravity exactly where it always is at this point with this beer. 
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 14, 2018, 09:26:22 PM
Awesome
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 15, 2018, 12:26:03 AM
Trusting Novotný enough that I'm doing current batch without bothering with hydrometers.  Just checked mid fermentation, and OP's calculator with Novotný shows gravity exactly where it always is at this point with this beer.

I added the novotny equations to the Terrill sheet and will be tracking from now on. I have a suspicion that the Terrill equations are more accurate at higher levels of attenuation.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 15, 2018, 12:43:14 AM
Trusting Novotný enough that I'm doing current batch without bothering with hydrometers.  Just checked mid fermentation, and OP's calculator with Novotný shows gravity exactly where it always is at this point with this beer.

I added the novotny equations to the Terrill sheet and will be tracking from now on. I have a suspicion that the Terrill equations are more accurate at higher levels of attenuation.

Could be, I'll look forward to your reporting on that.  Since I don't need to know when to spund,  I'm really just checking midway and at the end of fermentation to make sure there hasn't been some irregularity that would indicate the need to get a fresh culture of yeast.  So consistency is more important to me than accuracy.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 15, 2018, 03:22:08 PM
^^^^^

Just took a sample of a fully fermented beer. Hydrometer: 1.012. Terill: 1.010. Novotný: 1.008.  Maybe I'll use refractometer on brew day, but maybe neither correction is really accurate on fermenting/fermented beer.  Look forward to more data.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 15, 2018, 03:25:29 PM
^^^^^

Just took a sample of a fully fermented beer. Hydrometer: 1.012. Terill: 1.010. Novotný: 1.008.  Maybe I'll use refractometer on brew day, but maybe neither correction is really accurate on fermenting/fermented beer.  Look forward to more data.

Terrill New Cubic or New Linear? New cubic tracks a bit higher than New Linear.

What was the O.G.?
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 15, 2018, 03:36:34 PM
^^^^^

Just took a sample of a fully fermented beer. Hydrometer: 1.012. Terill: 1.010. Novotný: 1.008.  Maybe I'll use refractometer on brew day, but maybe neither correction is really accurate on fermenting/fermented beer.  Look forward to more data.

Are you very confident in your correction factor?  Did you check calibration of both the hydro and refract in plain cool water before measuring?
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 15, 2018, 04:42:46 PM
^^^^^

Just took a sample of a fully fermented beer. Hydrometer: 1.012. Terill: 1.010. Novotný: 1.008.  Maybe I'll use refractometer on brew day, but maybe neither correction is really accurate on fermenting/fermented beer.  Look forward to more data.

Are you very confident in your correction factor?  Did you check calibration of both the hydro and refract in plain cool water before measuring?
^^^^^

Just took a sample of a fully fermented beer. Hydrometer: 1.012. Terill: 1.010. Novotný: 1.008.  Maybe I'll use refractometer on brew day, but maybe neither correction is really accurate on fermenting/fermented beer.  Look forward to more data.

Terrill New Cubic or New Linear? New cubic tracks a bit higher than New Linear.

What was the O.G.?


OG 12.7°P, whatever Terill is in th OP's calculator, yes, yes, and yes to Dave's questions.  I've had one other sample (fully fermented, different batch of same beer) give identical results.

At this point I have no problem with using a hydrometer at racking if I want a good FG.   I see no inaccuracy on wort, so the refractometer I will use to simplify brew day.  And I'll only have one reading, FG, to convert to (my preferred) Plato.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 15, 2018, 04:55:02 PM
^^^^^

Just took a sample of a fully fermented beer. Hydrometer: 1.012. Terill: 1.010. Novotný: 1.008.  Maybe I'll use refractometer on brew day, but maybe neither correction is really accurate on fermenting/fermented beer.  Look forward to more data.

Are you very confident in your correction factor?  Did you check calibration of both the hydro and refract in plain cool water before measuring?
^^^^^

Just took a sample of a fully fermented beer. Hydrometer: 1.012. Terill: 1.010. Novotný: 1.008.  Maybe I'll use refractometer on brew day, but maybe neither correction is really accurate on fermenting/fermented beer.  Look forward to more data.

Terrill New Cubic or New Linear? New cubic tracks a bit higher than New Linear.

What was the O.G.?


OG 12.7°P, whatever Terill is in th OP's calculator, yes, yes, and yes to Dave's questions.  I've had one other sample (fully fermented, different batch of same beer) give identical results.

At this point I have no problem with using a hydrometer at racking if I want a good FG.   I see no inaccuracy on wort, so the refractometer I will use to simplify brew day.  And I'll only have one reading, FG, to convert to (my preferred) Plato.

The OP calculator uses Terrill New Linear. New Cubic actually tracks closer to what you saw @ 1.0116
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 15, 2018, 05:00:10 PM
^^^^^

Just took a sample of a fully fermented beer. Hydrometer: 1.012. Terill: 1.010. Novotný: 1.008.  Maybe I'll use refractometer on brew day, but maybe neither correction is really accurate on fermenting/fermented beer.  Look forward to more data.

Are you very confident in your correction factor?  Did you check calibration of both the hydro and refract in plain cool water before measuring?
^^^^^

Just took a sample of a fully fermented beer. Hydrometer: 1.012. Terill: 1.010. Novotný: 1.008.  Maybe I'll use refractometer on brew day, but maybe neither correction is really accurate on fermenting/fermented beer.  Look forward to more data.

Terrill New Cubic or New Linear? New cubic tracks a bit higher than New Linear.

What was the O.G.?


OG 12.7°P, whatever Terill is in th OP's calculator, yes, yes, and yes to Dave's questions.  I've had one other sample (fully fermented, different batch of same beer) give identical results.

At this point I have no problem with using a hydrometer at racking if I want a good FG.   I see no inaccuracy on wort, so the refractometer I will use to simplify brew day.  And I'll only have one reading, FG, to convert to (my preferred) Plato.

The OP calculator uses Terrill New Linear. New Cubic actually tracks closer to what you saw @ 1.0116

Thanks, that is probably within the margin-of-eyeballing-hydrometer-in-carbonated-beer error;  what calculator uses that new cubic?
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 15, 2018, 05:03:22 PM
^^^^^

Just took a sample of a fully fermented beer. Hydrometer: 1.012. Terill: 1.010. Novotný: 1.008.  Maybe I'll use refractometer on brew day, but maybe neither correction is really accurate on fermenting/fermented beer.  Look forward to more data.

Are you very confident in your correction factor?  Did you check calibration of both the hydro and refract in plain cool water before measuring?
^^^^^

Just took a sample of a fully fermented beer. Hydrometer: 1.012. Terill: 1.010. Novotný: 1.008.  Maybe I'll use refractometer on brew day, but maybe neither correction is really accurate on fermenting/fermented beer.  Look forward to more data.

Terrill New Cubic or New Linear? New cubic tracks a bit higher than New Linear.

What was the O.G.?


OG 12.7°P, whatever Terill is in th OP's calculator, yes, yes, and yes to Dave's questions.  I've had one other sample (fully fermented, different batch of same beer) give identical results.

At this point I have no problem with using a hydrometer at racking if I want a good FG.   I see no inaccuracy on wort, so the refractometer I will use to simplify brew day.  And I'll only have one reading, FG, to convert to (my preferred) Plato.

The OP calculator uses Terrill New Linear. New Cubic actually tracks closer to what you saw @ 1.0116

Thanks, that is probably within the margin-of-eyeballing-hydrometer-in-carbonated-beer error;  what calculator uses that new cubic?

Sean Terrill's Excel sheet uses it.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 15, 2018, 05:06:35 PM
Thanks, Big Monk, I'm looking at that right now.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 15, 2018, 05:08:13 PM
Thanks, Big Monk, I'm looking at that right now.

I just PM'd you my sheet that I modified. It is expanded to include the Novotny equations as well and reworks some of the Attenuation and Alcohol calcs as well to more accurate versions.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 15, 2018, 05:19:02 PM
Thanks, Big Monk, I'm looking at that right now.

I just PM'd you my sheet that I modified. It is expanded to include the Novotny equations as well and reworks some of the Attenuation and Alcohol calcs as well to more accurate versions.

Hands down, your sheet is the best thing I've seen yet.  Comprehensive and clear.  Thanks much!
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 17, 2018, 03:31:44 PM
Hydrometer: 1.012.  Refractometer WRIf: 6.  OG: 12.4°P.  Correction factor: 0.97. New Cubic wins again: sg1.0119.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 17, 2018, 11:08:22 PM
Hydrometer: 1.012.  Refractometer WRIf: 6.  OG: 12.4°P.  Correction factor: 0.97. New Cubic wins again: sg1.0119.

I find new Cubic to be the most accurate for me. I typically have Attenuation in the upper 80s and new Cubic seems to favor high Attenuation. New linear seems to work well for Attenuation in the low 80s.

Checking back through my numbers, Novotny would overshoot on every batch.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 17, 2018, 11:34:25 PM
Which Terrill would also be known as "linear"? That's what the Refractometer Calc app uses... Which I use too

My typical attenuation is 75-80%
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 17, 2018, 11:47:22 PM
Hydrometer: 1.012.  Refractometer WRIf: 6.  OG: 12.4°P.  Correction factor: 0.97. New Cubic wins again: sg1.0119.

I find new Cubic to be the most accurate for me. I typically have Attenuation in the upper 80s and new Cubic seems to favor high Attenuation. New linear seems to work well for Attenuation in the low 80s.

Checking back through my numbers, Novotny would overshoot on every batch.
Derek, it's looking pretty clear to me that new cubic is most accurate for FG.  But do you have any insight yet into whether Novotný is closer on partially fermented beer, or is that jury still out?
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 18, 2018, 12:43:23 AM
Which Terrill would also be known as "linear"? That's what the Refractometer Calc app uses... Which I use too

My typical attenuation is 75-80%

If you download Sean’s excel sheet, he has them labeled. It’s essentially the Cubic equation with the squared and cubed terms left off.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 18, 2018, 12:51:03 AM
Hydrometer: 1.012.  Refractometer WRIf: 6.  OG: 12.4°P.  Correction factor: 0.97. New Cubic wins again: sg1.0119.

I find new Cubic to be the most accurate for me. I typically have Attenuation in the upper 80s and new Cubic seems to favor high Attenuation. New linear seems to work well for Attenuation in the low 80s.

Checking back through my numbers, Novotny would overshoot on every batch.
Derek, it's looking pretty clear to me that new cubic is most accurate for FG.  But do you have any insight yet into whether Novotný is closer on partially fermented beer, or is that jury still out?

Honestly I don’t. I have to question whether there is even any utility in knowing mid fermentation gravity. When we spund, we are typically doing it with 4 points or so remaining and that’s close enough to final gravity that Terrill’s equation are bang on for me and most of the rest of the LOB crowd.

Maybe I’m being a bit short sighted? Is there a reason why we would even care about mid fermantion gravity? If not, then that gets rid of one of the major selling points for the Novotny equations. Add that to the fact that, for my beers at least, it’s wildly innacurate (estimated a correlation far lower than actual).

I do plan on entering data into my modified sheet over the next 10 batches or so and seeing how it turns out.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on February 18, 2018, 12:58:50 AM
I can only think of a few possible reasons. If you do a mid fermentation temp change. If you are tracking rate of fermentation. If you just have morbid curiosity and can't help but fiddle with things. Personally, I've done them all but they aren't really vital, at all
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 18, 2018, 01:00:41 AM
Hydrometer: 1.012.  Refractometer WRIf: 6.  OG: 12.4°P.  Correction factor: 0.97. New Cubic wins again: sg1.0119.

I find new Cubic to be the most accurate for me. I typically have Attenuation in the upper 80s and new Cubic seems to favor high Attenuation. New linear seems to work well for Attenuation in the low 80s.

Checking back through my numbers, Novotny would overshoot on every batch.
Derek, it's looking pretty clear to me that new cubic is most accurate for FG.  But do you have any insight yet into whether Novotný is closer on partially fermented beer, or is that jury still out?

Honestly I don’t. I have to question whether there is even any utility in knowing mid fermentation gravity. When we spund, we are typically doing it with 4 points or so remaining and that’s close enough to final gravity that Terrill’s equation are bang on for me and most of the rest of the LOB crowd.

Maybe I’m being a bit short sighted? Is there a reason why we would even care about mid fermantion gravity? If not, then that gets rid of one of the major selling points for the Novotny equations. Add that to the fact that, for my beers at least, it’s wildly innacurate (estimated a correlation far lower than actual).

I do plan on entering data into my modified sheet over the next 10 batches or so and seeing how it turns out.

I check mid fermentation because, fermenting lagers with 34/70, I let the temperature start to free rise at about 50% apparent attenuation.  But honestly, I don't use a gravity reading as my cue.  With countless batches behind me, I know by the number of hours from pitching when to cut attemperation.  But I do take a sample and check gravity just because if it were much higher or lower than expected at that point in time, that would indicate a problem with yeast, and I wouldn't repitch.  But for that purpose I can easily live with an error of +/- 0.5°P.  Or a bit more.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 18, 2018, 01:10:32 AM
Hydrometer: 1.012.  Refractometer WRIf: 6.  OG: 12.4°P.  Correction factor: 0.97. New Cubic wins again: sg1.0119.

I find new Cubic to be the most accurate for me. I typically have Attenuation in the upper 80s and new Cubic seems to favor high Attenuation. New linear seems to work well for Attenuation in the low 80s.

Checking back through my numbers, Novotny would overshoot on every batch.
Derek, it's looking pretty clear to me that new cubic is most accurate for FG.  But do you have any insight yet into whether Novotný is closer on partially fermented beer, or is that jury still out?

Honestly I don’t. I have to question whether there is even any utility in knowing mid fermentation gravity. When we spund, we are typically doing it with 4 points or so remaining and that’s close enough to final gravity that Terrill’s equation are bang on for me and most of the rest of the LOB crowd.

Maybe I’m being a bit short sighted? Is there a reason why we would even care about mid fermantion gravity? If not, then that gets rid of one of the major selling points for the Novotny equations. Add that to the fact that, for my beers at least, it’s wildly innacurate (estimated a correlation far lower than actual).

I do plan on entering data into my modified sheet over the next 10 batches or so and seeing how it turns out.

I check mid fermentation because, fermenting lagers with 34/70, I let the temperature start to free rise at about 50% apparent attenuation.  But honestly, I don't use a gravity reading as my cue.  With countless batches behind me, I know by the number of hours from pitching when to cut attemperation.  But I do take a sample and check gravity just because if it were much higher or lower than expected at that point in time, that would indicate a problem with yeast, and I wouldn't repitch.  But for that purpose I can easily live with an error of +/- 0.5°P.  Or a bit more.

The good thing is, if you track across a number of batches at different points and check with a hydrometer, you will then have a data set that are let’s you tell yourself which correlation works for which stage in fermentation.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 18, 2018, 01:18:54 AM
^^^^
Really, I'm thinking I can just start using a refractometer for the midway check and learn a new benchmark.   If the refractometer regularly reads x °P at y hours, that's all I need to know to track consistent yeast performance.  The "real" number is irrelevant. But knowing the right correction would be nice.  Maybe just a little anal.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 21, 2018, 03:16:59 AM
FWIW made one more actual comparison with hydrometer on another batch at FG today.  Terill new cubic dead on.  Done with this.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 21, 2018, 03:25:21 AM
FWIW made one more actual comparison with hydrometer on another batch at FG today.  Terill new cubic dead on.  Done with this.

For me it’s New Linear in the 78-82% AA range and New Cubic in the 83-89% AA range.
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 21, 2018, 04:03:10 AM
This is crazy.  We're all getting different answers.  Novotny and Old Cubic are most accurate for mine all the way across.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 21, 2018, 04:13:06 AM
This is crazy.  We're all getting different answers.  Novotny and Old Cubic are most accurate for mine all the way across.

I modified my sheet to calculate attenuation and alcohol for each correlation and entered in stats from 12 sessions. Novotny Linear and Cubic and Old Cubic WAY undershot every batch and returned unrealistic attenuation and ABV Numbers.
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 21, 2018, 04:18:19 AM
This is crazy.  We're all getting different answers.  Novotny and Old Cubic are most accurate for mine all the way across.

I modified my sheet to calculate attenuation and alcohol for each correlation and entered in stats from 12 sessions. Novotny Linear and Cubic and Old Cubic WAY undershot every batch and returned unrealistic attenuation and ABV Numbers.

And I get the opposite, from 5 data points though, not 12.  Maybe I'll change my tune after 12.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 21, 2018, 04:24:51 AM
This is crazy.  We're all getting different answers.  Novotny and Old Cubic are most accurate for mine all the way across.
I'm almost ready to propose a surprisingly commonsense solution.  We need no correction beyond our well-known factor for our own instrument for wort.  Simplify brew day by using refracto.  Ignore mid fermentation.  Use a hydro for FG, but wait until time tells you you're probably there.  You can surely afford one hydro size sample even on a small batch.  I have a vague recollection this is how we homebrewers first got interested in refractometers.
Title: Re: Improved Refractometer Correction calculator
Post by: DeeGood888 on February 21, 2018, 10:17:29 AM
Need to bookmark this  ;D
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 21, 2018, 12:52:30 PM
This is crazy.  We're all getting different answers.  Novotny and Old Cubic are most accurate for mine all the way across.

I modified my sheet to calculate attenuation and alcohol for each correlation and entered in stats from 12 sessions. Novotny Linear and Cubic and Old Cubic WAY undershot every batch and returned unrealistic attenuation and ABV Numbers.

And I get the opposite, from 5 data points though, not 12.  Maybe I'll change my tune after 12.

Just to satisfy my own curiosoty Dave: Why the fudge factors in your old cubic and Novotny linear calculations? Is it just that those modified values are just closer than the New cubic and New Linear calcs so you call that good?
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on February 21, 2018, 01:13:02 PM
Just to satisfy my own curiosoty Dave: Why the fudge factors in your old cubic and Novotny linear calculations? Is it just that those modified values are just closer than the New cubic and New Linear calcs so you call that good?

Yes.  Trying to fit the line better, assuming the curvature is correct but vertical placement is not.  Call my versions "the Taylor formulae" if you prefer.  Originally, I had applied fudge factors to Terrill's formulae based on Terrill's own analysis... but found those fudgers unnecessary to fit my own data set.  The reasons for doing so were sound enough for me to go ahead and use fudgers for other formulae where necessary.  See writeup from Terrill here, where he suggests his own New Cubic averages high by about 0.0007, but the Old Cubic was low by about 0.0017... so I added those fudge factors into my own spreadsheet originally right off the bat, then tweaked from there based on the line in my spreadsheet marked "New ABS Method" with a goal of zero of course, which unlike Terrill's "Mean discrepancy" which blends negative and positive values, my method uses absolute value distances from the goal line, yadda yadda.  Anyway...... here's Terrill's own analysis of the accuracy of his own formulae:

http://seanterrill.com/2011/04/07/refractometer-fg-results/

I guess you could say, I am attempting to normalize the playing field, instead of allowing each formula to average too high or too low.  Let's assume the curvature is correct but for some reason the people taking measurements aren't calibrating their hydrometer accurately, or whatever, which would result in a consistently high or low correlation.

There you have it.  I'm finally done editing this post (edited it about 6 times in the past 8 minutes).
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 21, 2018, 01:28:57 PM
^^^^^
Wherein Terrill says:

"In situations where the FG needs to be known precisely, testing with a properly calibrated precision hydrometer remains the best option."
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on February 21, 2018, 01:30:07 PM
Just to satisfy my own curiosoty Dave: Why the fudge factors in your old cubic and Novotny linear calculations? Is it just that those modified values are just closer than the New cubic and New Linear calcs so you call that good?

Yes.  Trying to fit the line better, assuming the curvature is correct but vertical placement is not.  Call my versions "the Taylor formulae" if you prefer.  Originally, I had applied fudge factors to Terrill's formulae based on Terrill's own analysis... but found those fudgers unnecessary to fit my own data set.  The reasons for doing so were sound enough for me to go ahead and use fudgers for other formulae where necessary.  See writeup from Terrill here, where he suggests his own New Cubic averages high by about 0.0007, but the Old Cubic was low by about 0.0017... so I added those fudge factors into my own spreadsheet originally right off the bat, then tweaked from there based on the line in my spreadsheet marked "New ABS Method" with a goal of zero of course, which unlike Terrill's "Mean discrepancy" which blends negative and positive values, my method uses absolute value distances from the goal line, yadda yadda.  Anyway...... here's Terrill's own analysis of the accuracy of his own formulae:

http://seanterrill.com/2011/04/07/refractometer-fg-results/

I guess you could say, I am attempting to normalize the playing field, instead of allowing each formula to average too high or too low.  Let's assume the curvature is correct but for some reason the people taking measurements aren't calibrating their hydrometer accurately, or whatever, which would result in a consistently high or low correlation.

There you have it.  I'm finally done editing this post (edited it about 6 times in the past 8 minutes).

Understood. I'm backfitting old data so it will be nice to log the next 8-10 sessions with fresh eyes and see where I land.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 23, 2018, 02:10:46 AM
I have a new set of precision Plato saccharometers arriving tomorrow.   Over time I will try to provide you guys some more data.  Will confirm my correction factor and post any measurements on this thread.

EDIT Perhaps it would be more helpful if I just posted raw data for batches where available:  OG,  mid, and FG  WRI  and saccharometer readings.  Let me know if it would be of any use.
Title: Re: Improved Refractometer Correction calculator
Post by: Pricelessbrewing on February 26, 2018, 02:20:19 AM
I have a new set of precision Plato saccharometers arriving tomorrow.   Over time I will try to provide you guys some more data.  Will confirm my correction factor and post any measurements on this thread.

EDIT Perhaps it would be more helpful if I just posted raw data for batches where available:  OG,  mid, and FG  WRI  and saccharometer readings.  Let me know if it would be of any use.

Give me all of the data!
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 26, 2018, 02:33:39 AM
I have a new set of precision Plato saccharometers arriving tomorrow.   Over time I will try to provide you guys some more data.  Will confirm my correction factor and post any measurements on this thread.

EDIT Perhaps it would be more helpful if I just posted raw data for batches where available:  OG,  mid, and FG  WRI  and saccharometer readings.  Let me know if it would be of any use.

Give me all of the data!
Will do.  Brewed Pils yesterday, will probably get a mid fermentation reading mid week, FG by next week.  I'll post a batch of data then. These pro brewery saccharometers are very easy to read; refractometer is an eye strain by comparison!  But I have confirmed the correction I've been using.
Title: Re: Improved Refractometer Correction calculator
Post by: hackrsackr on February 26, 2018, 04:45:43 AM
I have a new set of precision Plato saccharometers arriving tomorrow.   Over time I will try to provide you guys some more data.  Will confirm my correction factor and post any measurements on this thread.

EDIT Perhaps it would be more helpful if I just posted raw data for batches where available:  OG,  mid, and FG  WRI  and saccharometer readings.  Let me know if it would be of any use.

Give me all of the data!
Will do.  Brewed Pils yesterday, will probably get a mid fermentation reading mid week, FG by next week.  I'll post a batch of data then. These pro brewery saccharometers are very easy to read; refractometer is an eye strain by comparison!  But I have confirmed the correction I've been using.

Link to the saccharometers?


Sent from my iPhone using Tapatalk
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on February 26, 2018, 05:20:53 AM
^^^^
Here's the link.

Brix Saccharometer (7.5-16) https://www.amazon.com/dp/B01H3X2NUG/ref=cm_sw_r_cp_apap_OiXfhDZFmyj7T

  It may just give you one, but look down to "frequently bought together. "   There's a deal on the 0°-8.5°P and 7.5°-16°P; above that is, for most of us, mash density where we want to use a refractometer,  but they have one more at higher range if you keep searching.  This is a high grade professional brewery instrument. No buyer's remorse at all.

EDIT  Just a point of information,  you need a 14" test jar and a ~175-200ml sample.

Further point of info: these are marked at gradations of 0.1°P and there is a built in thermometer and correction scale, of course.
Title: Re: Improved Refractometer Correction calculator
Post by: hackrsackr on February 26, 2018, 05:29:17 AM
^^^^
Here's the link.

Brix Saccharometer (7.5-16) https://www.amazon.com/dp/B01H3X2NUG/ref=cm_sw_r_cp_apap_OiXfhDZFmyj7T

  It may just give you one, but look down to "frequently bought together. "   There's a deal on the 0°-8.5°P and 7.5°-16°P; above that is, for most of us, mash density where we want to use a refractometer,  but they have one more at higher range if you keep searching.  This is a high grade professional brewery instrument. No buyer's remorse at all.
Awesome! Thanks, Robert.


Sent from my iPhone using Tapatalk
Title: Re: Improved Refractometer Correction calculator
Post by: Petr on March 01, 2018, 12:49:47 AM
I would just like to mention that the main benefit of my formulae is that it does work for fermenting wort. For the well-attenuated beer, Terrill's and my result aren't too different. I would say they're within an experimental error.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on March 01, 2018, 01:04:13 AM
I would just like to mention that the main benefit of my formulae is that it does work for fermenting wort. For the well-attenuated beer, Terrill's and my result aren't too different. I would say they're within an experimental error.
I would agree for the most part, Petr.  Despite my offer above of more mid fermentation data for others on this forum, I've actually concluded based on my log records that I trust your formulae for mid fermentation.  But like some others here I have yet to be convinced that Terrill's new cubic is not more accurate for finished beer in a normal range of attenuation.  But thanks to you, I feel I have a good tool for determining when I have reached 50% apparent attenuation, where I start raising the temperature on my lager fermentations! 
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on March 01, 2018, 04:06:32 AM
I would just like to mention that the main benefit of my formulae is that it does work for fermenting wort. For the well-attenuated beer, Terrill's and my result aren't too different. I would say they're within an experimental error.

I find the opposite to be true. I brew only Trappist style ales and my attenuation is routinely > 85%. Your calculations seem to overshoot my actuals by a wide margin, in some cases as high as -0.006 S.G. Points from actual. I’m fairly confident I have entered the calculations faithfully in my spreadsheet, as they match the calculators that use your equations. 

For me, Terrill Cubic is king above 82% AA, and Terrill Linear for 78-82% AA.

I’ll also say that the above is true for values 4-6 points above final gravity as well, which is important for me as I use spunding.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on March 01, 2018, 04:45:23 AM
But in the 50% range Petr has it nailed down.  Derek, I'm using your sheet  now and (provisionally)  cherry picking at each stage of attenuation guided by experience.  It's handy that you have all of the calculations laid out in one place.  Cheers.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on March 01, 2018, 11:16:50 AM
But in the 50% range Petr has it nailed down.  Derek, I'm using your sheet  now and (provisionally)  cherry picking at each stage of attenuation guided by experience.  It's handy that you have all of the calculations laid out in one place.  Cheers.

Why are you raising the temperature again? Have you tried traditional cold fermentation and held at 45-48 °F the Whole time?
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on March 01, 2018, 05:06:10 PM
But in the 50% range Petr has it nailed down.  Derek, I'm using your sheet  now and (provisionally)  cherry picking at each stage of attenuation guided by experience.  It's handy that you have all of the calculations laid out in one place.  Cheers.

Why are you raising the temperature again? Have you tried traditional cold fermentation and held at 45-48 °F the Whole time?

Yes, I've done that.   I really don't want to derail this one a fermentation discussion, but :  each process in brewing has it's optimum conditions.  Think step mash.  Flavor maturation and attenuation are best achieved at 60°-64°F, and physical stabilization at 28°-30°F.  A compromise program of 48°-50°F and 37°-39°F misses the optima on both.  And it's not any more "traditional" if that matters.  It's based on the Summer or March beer process, rendered obsolete with refrigeration.  Traditional "Lager" or "Winter" beers were fermented more rapidly at warmer temps and held cold for as little as 7-10 days to clarify before serving.


BTW:  refractometer correction 0.97 OG 12.4°P FG: WRIf 6.0 saccharometer 3.1°P. 
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on March 01, 2018, 06:04:08 PM
But in the 50% range Petr has it nailed down.  Derek, I'm using your sheet  now and (provisionally)  cherry picking at each stage of attenuation guided by experience.  It's handy that you have all of the calculations laid out in one place.  Cheers.

Why are you raising the temperature again? Have you tried traditional cold fermentation and held at 45-48 °F the Whole time?

Yes, I've done that.   I really don't want to derail this one a fermentation discussion, but :  each process in brewing has it's optimum conditions.  Think step mash.  Flavor maturation and attenuation are best achieved at 60°-64°F, and physical stabilization at 28°-30°F.  A compromise program of 48°-50°F and 37°-39°F misses the optima on both. 

I was just assuming that you raise for a diacetyl rest, which typically is not required given cold temperatures, healthy pitches, step mashing/nutrient additions (wort production can affect nutrient levels in wort), etc. as the diacetyl precursor is less abundant.

Not knocking what you do, just bringing up another method that would save you having to raise the temperature, as well as eliminate the need for 50% AA checks. In the end you have a method that works in your brewery so I'm not trying to steer you either way, just curious was all.
Title: Re: Improved Refractometer Correction calculator
Post by: Petr on March 01, 2018, 06:43:10 PM
I would just like to mention that the main benefit of my formulae is that it does work for fermenting wort. For the well-attenuated beer, Terrill's and my result aren't too different. I would say they're within an experimental error.

I find the opposite to be true. I brew only Trappist style ales and my attenuation is routinely > 85%. Your calculations seem to overshoot my actuals by a wide margin, in some cases as high as -0.006 S.G. Points from actual. I’m fairly confident I have entered the calculations faithfully in my spreadsheet, as they match the calculators that use your equations. 

For me, Terrill Cubic is king above 82% AA, and Terrill Linear for 78-82% AA.

I’ll also say that the above is true for values 4-6 points above final gravity as well, which is important for me as I use spunding.

Well, I have never seen so large difference between the two methods for fully-attenuated beers. Can you provide me with some of your data, I would like to check that out? The data that were used to get my formulae was from hundreds of samples, although the strongest was 18 P, therefore it is possible that for stronger beer it can be less accurate. Or it can be simply because of wort correction factor. What kind of value do you use?

In many cases, and I'm not saying it is your case, people misuse the refractometer and hydrometer. The wort correction factor is good example. I was quite lucky and my factor is 1.00, although it vary a lot, and I have friends that have 0.90 or even 1.1. If someone is using in good belief standard value of 1.04 it can be pretty far from the reality. A friend of mine has also a refractometer that he must calibrate on the water every single time before measurement. I just want to say that that cheap refractometers can be quite tricky to use accurately.

The accuracy itself is another issue. The hydrometer should be used with decarbonated wort only but not all of as do that. That can make difference order of 0.001 SG. Then there is a temperature, +-10F from calibration temperature can make +-0.001 SG. In case of the refractometer, they have usually accuracy around 0.2 Bx (0.001 SG) and into formulae you're feeding it twice. For beer before bottling it is often even worse, and the sample can be pretty fuzzy on refractometer's glass. So I would say, that you cannot expect the accuracy of FG from formulae to be better than 0.001-0.002 depending on particular circumstances, sometimes worse.

So, if all of these aspects are not ideal in some particular case, there is no point in chasing which formulae is better. In some cases, even worse formulae can give you better results if the input is not ideal it can cancel out some of that "non-ideality".

My formula is actually quite connected to Balling's formula that is widely used for its overall accuracy, although there could be cases when beer deviates from that formula, and there is no doubt about that even if it's less common than the other case.   



Title: Re: Improved Refractometer Correction calculator
Post by: Robert on March 04, 2018, 02:20:49 PM
I've now measured 3 batches at FG since getting the professional brewery saccharometers,  and all 3 have shown Terrill new LINEAR to be dead on.  FWIW.  I'm convinced refractometers are good during mashing.  For chilled wort and fermentation, go with a floaty thing, not an optical delusion. ;D
Title: Re: Improved Refractometer Correction calculator
Post by: Pricelessbrewing on March 04, 2018, 06:35:56 PM
I haven't been following all 13 pages very closely, but I'm happy to see you on here now petr, and that there have been translations done.

Is the data you use publicly available anywhere?

Were different yeast types used and categorized? Specifically I'm interested in if the curve is different for diastaticus yeast vs brett vs more common ale or lager yeasts.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on March 05, 2018, 03:29:54 AM
I would just like to mention that the main benefit of my formulae is that it does work for fermenting wort. For the well-attenuated beer, Terrill's and my result aren't too different. I would say they're within an experimental error.

I find the opposite to be true. I brew only Trappist style ales and my attenuation is routinely > 85%. Your calculations seem to overshoot my actuals by a wide margin, in some cases as high as -0.006 S.G. Points from actual. I’m fairly confident I have entered the calculations faithfully in my spreadsheet, as they match the calculators that use your equations. 

For me, Terrill Cubic is king above 82% AA, and Terrill Linear for 78-82% AA.

I’ll also say that the above is true for values 4-6 points above final gravity as well, which is important for me as I use spunding.

Well, I have never seen so large difference between the two methods for fully-attenuated beers. Can you provide me with some of your data, I would like to check that out? The data that were used to get my formulae was from hundreds of samples, although the strongest was 18 P, therefore it is possible that for stronger beer it can be less accurate. Or it can be simply because of wort correction factor. What kind of value do you use?

In many cases, and I'm not saying it is your case, people misuse the refractometer and hydrometer. The wort correction factor is good example. I was quite lucky and my factor is 1.00, although it vary a lot, and I have friends that have 0.90 or even 1.1. If someone is using in good belief standard value of 1.04 it can be pretty far from the reality. A friend of mine has also a refractometer that he must calibrate on the water every single time before measurement. I just want to say that that cheap refractometers can be quite tricky to use accurately.

The accuracy itself is another issue. The hydrometer should be used with decarbonated wort only but not all of as do that. That can make difference order of 0.001 SG. Then there is a temperature, +-10F from calibration temperature can make +-0.001 SG. In case of the refractometer, they have usually accuracy around 0.2 Bx (0.001 SG) and into formulae you're feeding it twice. For beer before bottling it is often even worse, and the sample can be pretty fuzzy on refractometer's glass. So I would say, that you cannot expect the accuracy of FG from formulae to be better than 0.001-0.002 depending on particular circumstances, sometimes worse.

So, if all of these aspects are not ideal in some particular case, there is no point in chasing which formulae is better. In some cases, even worse formulae can give you better results if the input is not ideal it can cancel out some of that "non-ideality".

My formula is actually quite connected to Balling's formula that is widely used for its overall accuracy, although there could be cases when beer deviates from that formula, and there is no doubt about that even if it's less common than the other case.

Thank you for this post Petr.

I want to be clear: I am backfitting old info. I have reasonable assurance that I was careful to calibrate and prepare samples but some of these batches are old.

I am going to be tracking your equations and Terrill’s in the foreseeable future to see if these new results square with the old stuff. The way my sheet is structured I can compare all 5 correlations simultaneously.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on March 06, 2018, 07:24:46 PM
This is crazy.  We're all getting different answers.  Novotny and Old Cubic are most accurate for mine all the way across.

Been thinking about this whole thing.

I suspect a source of difficulty is the assumption being made that the only difference to account for between wort and beer is the presence of alcohol. In fact of course many other fermentation products are present (CO2 can be ignored as it is expressed from under the cover plate of the refractometer. )

The more I test, the more I find different formulae working at different times and in different batches.  The differences between the beers are seemingly minor and various:   slight variations in the blend of malts, amounts and varieties of hops used, attenuation limit, generation and pitch rate of the yeast, and so on.  (You know, always dialing in the recipe!)  But each of these factors could have a significant effect on the chemical composition of the fermenting/fermented beer, and I suspect in turn a significant effect on the refractivity index.   So every beer, or at least every set of samples produced identically, would really require its own correction formula.  And that formula could only be modeled retroactively once you already have a full analyses of the beer, and so would be superfluous.

  Refractivity and density just don't correlate except as determined for a specific substance.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on March 08, 2018, 12:45:27 AM
This is crazy.  We're all getting different answers.  Novotny and Old Cubic are most accurate for mine all the way across.

Been thinking about this whole thing.

I suspect a source of difficulty is the assumption being made that the only difference to account for between wort and beer is the presence of alcohol. In fact of course many other fermentation products are present (CO2 can be ignored as it is expressed from under the cover plate of the refractometer. )

The more I test, the more I find different formulae working at different times and in different batches.  The differences between the beers are seemingly minor and various:   slight variations in the blend of malts, amounts and varieties of hops used, attenuation limit, generation and pitch rate of the yeast, and so on.  (You know, always dialing in the recipe!)  But each of these factors could have a significant effect on the chemical composition of the fermenting/fermented beer, and I suspect in turn a significant effect on the refractivity index.   So every beer, or at least every set of samples produced identically, would really require its own correction formula.  And that formula could only be modeled retroactively once you already have a full analyses of the beer, and so would be superfluous.

  Refractivity and density just don't correlate except as determined for a specific substance.

A good method would be to save wort from Losses and determine that batches correction after you put it into the fermenter. Essentially calibrate after racking over for every batch and log it into the spreadsheet. The. There is no guessing and the numbers for that batch are rock solid and stored for posterity.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on March 08, 2018, 01:09:12 AM
Wort seems consistent with respect to my instrument's correction factor.  It's fermentation products other than alcohol, as I said, that I don't think are adequately accounted for.  (The only definitive test for alcohol content, after all, is to remove it and compare the weight or volume of the resulting sample.) The composition of the beer is complex and continually changing.  I have no doubt that some formula would work every time if all we did was progressively dilute the initial wort sample with pure alcohol!
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on March 08, 2018, 01:46:48 AM
Wort seems consistent with respect to my instrument's correction factor.  It's fermentation products other than alcohol, as I said, that I don't think are adequately accounted for.  (The only definitive test for alcohol content, after all, is to remove it and compare the weight or volume of the resulting sample.) The composition of the beer is complex and continually changing.  I have no doubt that some formula would work every time if all we did was progressively dilute the initial wort sample with pure alcohol!

I’m not big on variety so I think I’ll trust what I see after checking 5-6 batches with Hydrometer and Refrac. All my Trappist style beers have the same original gravity pre-sugar, so I’ll have one correction factor for all preboil wort, and then one separate fermentation correction factor for each beer.
Title: Re: Improved Refractometer Correction calculator
Post by: Petr on March 11, 2018, 11:30:47 PM
I haven't been following all 13 pages very closely, but I'm happy to see you on here now petr, and that there have been translations done.

Is the data you use publicly available anywhere?

Were different yeast types used and categorized? Specifically I'm interested in if the curve is different for diastaticus yeast vs brett vs more common ale or lager yeasts.

Yes, they are. I used literature data (professionally obtained with way more accurate equipment that we usually have), the original article can be found here https://www.researchgate.net/publication/307794886_Convenient_Monitoring_Of_Brewery_Fermentation_Course_By_Refractometry.

It works for fermentation in general as long as yeast follow Balling's laws. I guess it should work for those that you mentioned but I tried that only on the bottom and top-fermenting yeasts of various strains. One small fermentation should be enough to validate it for you. Basically, you just need to confirm that the metabolism of those yeasts is or is not the same (for practical purposes) as for brewers yeast. I would say that chances are rather high that it is. 

Title: Re: Improved Refractometer Correction calculator
Post by: Petr on March 11, 2018, 11:36:37 PM
This is crazy.  We're all getting different answers.  Novotny and Old Cubic are most accurate for mine all the way across.

Been thinking about this whole thing.

I suspect a source of difficulty is the assumption being made that the only difference to account for between wort and beer is the presence of alcohol. In fact of course many other fermentation products are present (CO2 can be ignored as it is expressed from under the cover plate of the refractometer. )

The more I test, the more I find different formulae working at different times and in different batches.  The differences between the beers are seemingly minor and various:   slight variations in the blend of malts, amounts and varieties of hops used, attenuation limit, generation and pitch rate of the yeast, and so on.  (You know, always dialing in the recipe!)  But each of these factors could have a significant effect on the chemical composition of the fermenting/fermented beer, and I suspect in turn a significant effect on the refractivity index.   So every beer, or at least every set of samples produced identically, would really require its own correction formula.  And that formula could only be modeled retroactively once you already have a full analyses of the beer, and so would be superfluous.

  Refractivity and density just don't correlate except as determined for a specific substance.

Yes, beer is a mixture of thousands of compounds but when compared to residual sugar, water and ethanol everything is negligible in terms of concentrations, their concentrations are a couple of order magnitudes lower than that "big three". Refractive index is concentration sensitive, thus small differences in concentrations of those "other" compounds do not have a significant effect on the measurement at our level of accuracy.

Every equation assumes some sort of balance between consumed sugar and produced ethanol. If the equation does not work precisely that simply means that particular beer does not follow the assumed balance. The balance can be theoretical or experimentally build in the equation - but it is always there. That is something that Balling figured it out in 1865 since then his equation is kind of golden standard although deviations from his balance/equation are known.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on March 12, 2018, 05:12:25 AM
I'm really enjoying my switch to refractometer only. But I think it works so well for me because I only care about 'close enough'. I'm actually considering picking up a Hannah digital next fall, just for fun. I read Marshall's review of it, and saw that when he tested final Plato with it he used Sean's 1.040 correction factor. My first thought was OMG! He should have read this thread. But for kicks I plugged in some arbitrary numbers. If the refractometer read 18 brix starting and 8 brix final, with a correction factor of 1 the actual FG is 1.013. If the correction factor was 1.0126 (mine) it finished at 1.012. If the correction factor was 1.04 the FG is 1.012. The 3 different correction factors end up covering a pretty narrow span between a total of .2% abv. I am so grateful that to me, that is totally close enough. But, I don't spund.

For now, my $12 Chinese refractometer is getting the job done. I have not touched my hydrometer in a couple months. I probably will treat myself to the $180 digital toy in the fall. I won't need to fumble with the tiny screw driver, or trying to line up my bifocals on the eyepiece. Just push a button and enter the number to my correction app.

For folks who don't spund, but still freak out about precision, I have a challenge for you. The next time you drink a commercial beer, one you don't know the numbers on, guess what the FG is. Write it down so you can't cheat. Then measure it. If you can't consistently and accurately taste the FG within +/- 1 gravity point, why does it really matter what your instruments and math says?
Title: Re: Improved Refractometer Correction calculator
Post by: Slowbrew on March 12, 2018, 11:09:50 AM
Jim is man with my own view of the world.  I too haven't used my hydrometer in years.  My refractometer gets me "close enough" and for me that's good enough.  I don't have to file federal paperwork or worry about audits so if my kegs don't explode, I'm happy.

Everyone's views have been interesting and informative but for me the need for perfection just isn't there.

Thanks Jim!

Paul
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on March 12, 2018, 11:32:49 AM
The last sentence of my "challenge" is worded as a question, not to be a smartie pants (well, maybe a little) but because it's entirely possible that I'm oblivious to why absolute accuracy is necessary.
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on March 12, 2018, 12:08:51 PM
I have a challenge for you. The next time you drink a commercial beer, one you don't know the numbers on, guess what the FG is. Write it down so you can't cheat. Then measure it. If you can't consistently and accurately taste the FG within +/- 1 gravity point, why does it really matter what your instruments and math says?

Yeah baby!!   8)
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on March 12, 2018, 12:24:14 PM
The last sentence of my "challenge" is worded as a question, not to be a smartie pants (well, maybe a little) but because it's entirely possible that I'm oblivious to why absolute accuracy is necessary.

I bottle with extract which is pretty much the only reason I care about accuracy. Unlike my keg Spunding brethren, I can’t bleed pressure once bottled.

I can’t see why anyone else would want to freak out.
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on March 12, 2018, 12:34:15 PM
The last sentence of my "challenge" is worded as a question, not to be a smartie pants (well, maybe a little) but because it's entirely possible that I'm oblivious to why absolute accuracy is necessary.

I bottle with extract which is pretty much the only reason I care about accuracy. Unlike my keg Spunding brethren, I can’t bleed pressure once bottled.

I can’t see why anyone else would want to freak out.

The only reason I get in this deep is due to my love for math and science.  But the more I sit back and think about it, the more I realize how much of an unnecessary expediture of time it all really is.

That said... ability to match within 0.001 of a hydro now is a mission accomplished, for me, here, using my cheap junk refractometer.  Yay.
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on March 12, 2018, 12:50:45 PM
The last sentence of my "challenge" is worded as a question, not to be a smartie pants (well, maybe a little) but because it's entirely possible that I'm oblivious to why absolute accuracy is necessary.

I bottle with extract which is pretty much the only reason I care about accuracy. Unlike my keg Spunding brethren, I can’t bleed pressure once bottled.

I can’t see why anyone else would want to freak out.

The only reason I get in this deep is due to my love for math and science.  But the more I sit back and think about it, the more I realize how much of an unnecessary expediture of time it all really is.

That said... ability to match within 0.001 of a hydro now is a mission accomplished, for me, here, using my cheap junk refractometer.  Yay.

I’ve actually come up with a really slick way of getting all the info I need in one fell swoop.

Since I test the base malts I buy for DI pH, I can make the test mash to the same gravity as the batch and get my correction factor for the batch at the outset.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on March 12, 2018, 01:05:14 PM
I did some deep diving on the interewebs this weekend, mostly threads on other forums (many I never knew existed) and some of the sources they led to.  Turns out there's a good amount of research confirming my suspicions above about many factors confounding corrections.  It seems hops alone can have an effect nearly as significant as alcohol, as can different grists, let alone all the other compounds in beer.  Much more research would be needed if it's even possible to develop reliable corrections, and the pros aren't going to do it, they don't use refractometers. We're just trying to use an instrument to measure something it wasn't designed to measure. (No I don't have all the references, you've got Google if you care.)

This looked good to me on a limited number of samples, but the more I've racked up, it looks like none of these formulas really works, which now doesn't surprise me.  If I have all the formulas in front of me (and thanks to Big Monk, I do!) I can find one of the half dozen that's fairly close.  But that just means that there's a one in six chance I can squint really hard and pretend it looks like something's working, not that it is.

So for my part, I'm back to the position that refractometers are useful pre-boil only, and I establish a correction factor for each individual batch using the saccharometer OG.  Even Terrill has said (referenced somewhere in this thread) that if you actually want to know FG (or for that matter when to spund) you really need a hydrometer.

So finally, if you're of the school of "close enough is close enough, I  don't  really need to know," why do you need any instrument at all?

  When it stops bubbling, its done!
Title: Re: Improved Refractometer Correction calculator
Post by: Petr on March 12, 2018, 03:00:31 PM
I did some deep diving on the interewebs this weekend, mostly threads on other forums (many I never knew existed) and some of the sources they led to.  Turns out there's a good amount of research confirming my suspicions above about many factors confounding corrections.  It seems hops alone can have an effect nearly as significant as alcohol, as can different grists, let alone all the other compounds in beer.  Much more research would be needed if it's even possible to develop reliable corrections, and the pros aren't going to do it, they don't use refractometers. We're just trying to use an instrument to measure something it wasn't designed to measure. (No I don't have all the references, you've got Google if you care.)

This looked good to me on a limited number of samples, but the more I've racked up, it looks like none of these formulas really works, which now doesn't surprise me.  If I have all the formulas in front of me (and thanks to Big Monk, I do!) I can find one of the half dozen that's fairly close.  But that just means that there's a one in six chance I can squint really hard and pretend it looks like something's working, not that it is.

So for my part, I'm back to the position that refractometers are useful pre-boil only, and I establish a correction factor for each individual batch using the saccharometer OG.  Even Terrill has said (referenced somewhere in this thread) that if you actually want to know FG (or for that matter when to spund) you really need a hydrometer.

So finally, if you're of the school of "close enough is close enough, I  don't  really need to know," why do you need any instrument at all?

  When it stops bubbling, its done!

I highly doubt that hop compounds can have a comparable effect on refractive index as alcohol that is just not possible from the chemistry point of view when hop compounds are there in ppm level and alcohol in a couple of %. Can you provide me with a work that you were referring to? I did my google research but didn't find anything close to that statement.

I'm normally just fine with +- 0.002 accuracy of FG, and for a long time now I use refractometer only. The main reason why I bothered with the new formula wasn't actually FG because for that purpose with reasonable accuracy you can use Terill's formula just fine. The reason was that sometimes I need also a reading during fermentation and don't want to waste about 100 mL of wort every time, especially if it is an experimental brew with total volume 2 litres and often less... The thing is that my formula works for wort during the whole fermentation and that is the main advantage of it. I know that not everyone is in need of measurements during fermentation but the option is there for those who need or/and want.

If you don't care about the FG at all then well no problem with that neither. It's up to every one of us.

Title: Re: Improved Refractometer Correction calculator
Post by: Robert on March 12, 2018, 03:46:04 PM
Sorry, I didn't save my search results.  I just kept reading until I was assured there really is something going on here to confirm my suspicions.  I think all the non-alcohol factors, in the aggregate, can have enough impact that a formula based on one set of samples will not apply universally.  But if you are only interested in a certain margin of accuracy, I'm sure you can establish a correlation that works for you.  This really doesn't bother me, I just plan my brew length with a spare liter or so to allow for all the samples I might want to pull.  I realize this is not feasible for small batch brewers. I don't really have skin in this game. The amount of discrepancy between formulae,  each of which was empirically derived, just bothered me.  I wanted some insight.  Now everyone should just do what works for them!
Title: Re: Improved Refractometer Correction calculator
Post by: narvin on March 12, 2018, 03:58:02 PM
On the flipside, what makes us think that density is a good measure of how the beer will taste?  It is well known that different sugars taste vastly different in a finished beer, so one 1.015 beer can taste sweet and another not at all.  Add alcohol into the density equation and you aren't even measuring one thing, but a balance - hence "apparent attenuation".  So, other than knowing when your beer is done, what is it really telling you?

I've been measuring with refractometer only for a while, and it tells me just as much about the final mouthfeel of a beer as density ever did.  It also helps to measure a variety of beer (commercial, other homebrews) and get an idea of what your target is for the style.  It's like going from F to C: you're never going to make the switch if you're constantly doing conversions in your head.  Think native!
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on March 12, 2018, 04:11:59 PM
I'm only interested in a reasonably accurate reading so I could spot any change in performance that would tell me not to repitch the yeast.  Otherwise, like I said, when it stops bubbling, its done!
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on March 12, 2018, 04:17:10 PM
I did some deep diving on the interewebs this weekend, mostly threads on other forums (many I never knew existed) and some of the sources they led to.  Turns out there's a good amount of research confirming my suspicions above about many factors confounding corrections.  It seems hops alone can have an effect nearly as significant as alcohol, as can different grists, let alone all the other compounds in beer.  Much more research would be needed if it's even possible to develop reliable corrections, and the pros aren't going to do it, they don't use refractometers. We're just trying to use an instrument to measure something it wasn't designed to measure. (No I don't have all the references, you've got Google if you care.)

This looked good to me on a limited number of samples, but the more I've racked up, it looks like none of these formulas really works, which now doesn't surprise me.  If I have all the formulas in front of me (and thanks to Big Monk, I do!) I can find one of the half dozen that's fairly close.  But that just means that there's a one in six chance I can squint really hard and pretend it looks like something's working, not that it is.

So for my part, I'm back to the position that refractometers are useful pre-boil only, and I establish a correction factor for each individual batch using the saccharometer OG.  Even Terrill has said (referenced somewhere in this thread) that if you actually want to know FG (or for that matter when to spund) you really need a hydrometer.

So finally, if you're of the school of "close enough is close enough, I  don't  really need to know," why do you need any instrument at all?

  When it stops bubbling, its done!
Robert, bubbling or lack of bubbling is not reliable. Getting two readings, days apart, which are the same... much more reliable way to determine it's done. What I'm talking about as "close enough" is whether it's 1.012 SG or 1.013 SG terminal.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on March 12, 2018, 04:34:24 PM
Sorry, I was using "bubbling" rather loosely and maybe being a little bit facetious.  What I mean is, when there is no sign of active fermentation, which you can determine any way you like.  I largely rely on time, knowing how long it takes my yeast to do the job.  Guess that's pretty much in the "close enough" school.

EDIT  I'm usually right on using time and temp, always within 0.2°P, which will finish out in lagering.  I'd have to be tighter if I bottled!
Title: Re: Improved Refractometer Correction calculator
Post by: Phil_M on March 12, 2018, 05:38:29 PM
The last sentence of my "challenge" is worded as a question, not to be a smartie pants (well, maybe a little) but because it's entirely possible that I'm oblivious to why absolute accuracy is necessary.

I bottle with extract which is pretty much the only reason I care about accuracy. Unlike my keg Spunding brethren, I can’t bleed pressure once bottled.

I can’t see why anyone else would want to freak out.

This is back to the typical accuracy vs. precision argument. I certainly don't trust ANY of my homebrewing measuring devices to be accurate, save for perhaps my thermapen. But if they're precise, that won't matter. With multiple batches repeatable measurements will be all that was needed.

After all, mark on a stick units are how most measurements started, from temperature to density. We're getting so down in the weeds of this debate that we're losing sight of the purpose.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on March 12, 2018, 08:11:21 PM
Yup. But that's cool. It's in our culture to bicker, but sometimes we should remember that we're all on the same side. Well, except people who dont like Fuggles!
Title: Re: Improved Refractometer Correction calculator
Post by: denny on March 12, 2018, 08:20:50 PM
Yup. But that's cool. It's in our culture to bicker, but sometimes we should remember that we're all on the same side. Well, except people who dont like Fuggles!

I represent that remark!
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on March 12, 2018, 08:22:59 PM
On the flipside, what makes us think that density is a good measure of how the beer will taste?  It is well known that different sugars taste vastly different in a finished beer, so one 1.015 beer can taste sweet and another not at all.  Add alcohol into the density equation and you aren't even measuring one thing, but a balance - hence "apparent attenuation".  So, other than knowing when your beer is done, what is it really telling you?

I've been measuring with refractometer only for a while, and it tells me just as much about the final mouthfeel of a beer as density ever did.  It also helps to measure a variety of beer (commercial, other homebrews) and get an idea of what your target is for the style.  It's like going from F to C: you're never going to make the switch if you're constantly doing conversions in your head.  Think native!
Thank you. Pretty much what I was trying to say. I'm on my way to speaking °P. I switched all of my recipes to it. Kind of forces the deal.
Title: Re: Improved Refractometer Correction calculator
Post by: klickitat jim on March 12, 2018, 08:24:30 PM
Yup. But that's cool. It's in our culture to bicker, but sometimes we should remember that we're all on the same side. Well, except people who dont like Fuggles!

I represent that remark!
Mister "dirt is cheaper"!

I'll double mash up Triple IPA with 100% brown malt and 100 IBUs of Fuggles, "Big Muddy"! Of course I'd need your feedback on every bottle
Title: Re: Improved Refractometer Correction calculator
Post by: denny on March 12, 2018, 08:28:57 PM
Yup. But that's cool. It's in our culture to bicker, but sometimes we should remember that we're all on the same side. Well, except people who dont like Fuggles!

I represent that remark!
Mister "dirt is cheaper"!

 ;D

Title: Re: Improved Refractometer Correction calculator
Post by: Petr on March 13, 2018, 01:35:03 PM
Sorry, I didn't save my search results.  I just kept reading until I was assured there really is something going on here to confirm my suspicions.  I think all the non-alcohol factors, in the aggregate, can have enough impact that a formula based on one set of samples will not apply universally.  But if you are only interested in a certain margin of accuracy, I'm sure you can establish a correlation that works for you.  This really doesn't bother me, I just plan my brew length with a spare liter or so to allow for all the samples I might want to pull.  I realize this is not feasible for small batch brewers. I don't really have skin in this game. The amount of discrepancy between formulae,  each of which was empirically derived, just bothered me.  I wanted some insight.  Now everyone should just do what works for them!

Robert, you're wrong there. First of all, none of the formulae are based on one set of samples only. Non-alcohol factors (as hop compounds etc.) are significant for taste but because of their low concentration the effect on refractive index is negligible for our practical purposes and unless you'll provide me with an appropriate reference of otherwise I'll believe that I understand my professional field. You're chasing the wrong issue, as I said the real problem is that in some instances yeast is not necessary following precisely the same material balance glucose->ethanole + CO2 + biomass. Secondly, you're wrong that each of the formulas was just empirically derived. If you would take a look at that original reference that I provided you would see that there was a lot of insight into that formula and its form has a strong theoretical background. That is precisely the reason why my formula works for the whole fermentation and not just only for well-attenuated beer.

As you said everyone should use what works for them. I just provided another option for those who are interested. I have plenty of feedback that it works just fine for a lot, and there are fewer that has opposite experience and reasons for that are unclear to me even if I'm well aware of its limitations. I would love to find out reasons but that cannot do until I will really know details of each case with the actual data. My experience is that in the majority of cases it is due to misuse of the instrument or/and formulae or too high expectations about accuracy that just simply can't be better than 0.001-0.002 depending on particular circumstances.

Title: Re: Improved Refractometer Correction calculator
Post by: Petr on March 13, 2018, 01:51:29 PM
On the flipside, what makes us think that density is a good measure of how the beer will taste?  It is well known that different sugars taste vastly different in a finished beer, so one 1.015 beer can taste sweet and another not at all.  Add alcohol into the density equation and you aren't even measuring one thing, but a balance - hence "apparent attenuation".  So, other than knowing when your beer is done, what is it really telling you?

I've been measuring with refractometer only for a while, and it tells me just as much about the final mouthfeel of a beer as density ever did.  It also helps to measure a variety of beer (commercial, other homebrews) and get an idea of what your target is for the style.  It's like going from F to C: you're never going to make the switch if you're constantly doing conversions in your head.  Think native!

No one claims that. FG is more of the process variable – it tells you how is the fermentation going, if it is done, how yeast performed, consistency between batches etc. with a deeper insight you can dig out even more. For instance, if yeast fermented maltotriose. It has also limited informational value about the body but that has to be considered in the whole picture of the taste. Yes, you're not measuring the variable directly and you're right that it measures the balance but the balance is relatively well understood with good accuracy for our purposes, so there is not much of the problem in that. The understanding allows us to measure things undirectly but reliably.

Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on March 13, 2018, 01:57:37 PM
Non-alcohol factors (as hop compounds etc.) are significant for taste but because of their low concentration the effect on refractive index is negligible for our practical purposes and unless you'll provide me with an appropriate reference of otherwise I'll believe that I understand my professional field. You're chasing the wrong issue...

Stronger wording eliminated, I agree with what was said right here above.  My sciency background brought me to the same conclusion: other chemical constituents besides water and ethanol are negligible and need not be considered here for refractometer measurements.  Their concentrations are just way way way too low to have any discernible effect on the margin of error.

Cheers.

David M. Taylor
B.S. Chemical Engineering
Michigan Tech
Class of 1997
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on March 13, 2018, 01:57:45 PM
I certainly defer to you, Petr.  I got into this discussion because I was curious as to why this didn't seem to work for me:  or at least only occasionally worked.  I may have misinterpreted some of what I read, or the writers did.  It seems many of us get higher FG readings with hydrometer than any of the formulas predict.  As I said, I don't need a refractometer except pre-boil.  For those who do, I hope they find your formula serves their needs. It's astonishing how many times essentially this same conversation has been repeated on various forums.  It seems there is great interest in refractometers,  but a few intractable gremlins in the works! Carry on the good work.  BTW I appreciated your recent article on hop utilization, too.
Title: Re: Improved Refractometer Correction calculator
Post by: Petr on March 13, 2018, 02:21:11 PM
I certainly defer to you, Petr.  I got into this discussion because I was curious as to why this didn't seem to work for me:  or at least only occasionally worked.  I may have misinterpreted some of what I read, or the writers did.  It seems many of us get higher FG readings with hydrometer than any of the formulas predict.  As I said, I don't need a refractometer except pre-boil.  For those who do, I hope they find your formula serves their needs. It's astonishing how many times essentially this same conversation has been repeated on various forums.  It seems there is great interest in refractometers,  but a few intractable gremlins in the works! Carry on the good work.  BTW I appreciated your recent article on hop utilization, too.

Hear, hear. You know it depends on every one of us. I prefer the refractometer just because of the convenience of it – take few drops of wort and in a minute you have the reading, accurate enough for my purposes. In other cases as for low volume fermentation tests that I do for example for yeast hunting, it is even a necessity because I just can't afford the volume needed for the hydrometer. Glad you like the hop article!

Title: Re: Improved Refractometer Correction calculator
Post by: ynotbrusum on March 13, 2018, 06:16:02 PM
I am grateful for you chemical engineering types for a deep discussion and interesting precision about gravity readings. 

I have no science background, though others in my family do.  I think I am just going back to my lab grade hydrometer (final gravity reading demarcation range only) and set up a small table of refractometer readings as compared to hydrometer readings for my typical low ABV beers over the next few batches.  That should get me in the ballpark, if I want to go with refractometer readings, alone.

I appreciate the deep water, but I think this is one area where I can't swim well enough and will have to watch from the knee deep level near shore.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on April 24, 2018, 01:24:33 PM
Don't want to get back into the weeds, just curious if anyone else who was having seriously questionable results with refractometer has seen improvement.  Tried it for kicks again last two batches.  During fermentation with actual saccharometer readings of 4.1°P and 4.5°P respectively, ALL the calculators gave results <0, so I didn't even bother when a batch finished out at 3.0°P.  Still use refractometer during mash, just still doesn't work for me in ferment.
Title: Re: Improved Refractometer Correction calculator
Post by: Petr on April 24, 2018, 01:36:44 PM
Don't want to get back into the weeds, just curious if anyone else who was having seriously questionable results with refractometer has seen improvement.  Tried it for kicks again last two batches.  During fermentation with actual saccharometer readings of 4.1°P and 4.5°P respectively, ALL the calculators gave results <0, so I didn't even bother when a batch finished out at 3.0°P.  Still use refractometer during mash, just still doesn't work for me in ferment.

I think that the answer for you if you're getting less then 0 as a result, is unfortunately simple. You're either using wrongly the calculators or your refractometer does not work as it is supposed to. What kind of refractometer do you have?
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on April 24, 2018, 01:43:18 PM
An optical hand type, although I have a digital one on order (I really do find refractometers handy in the mash, and this should simplify my brewing.)  Again, don't really need it post boil, just curious.
Title: Re: Improved Refractometer Correction calculator
Post by: Petr on April 24, 2018, 01:48:10 PM
An optical hand type, although I have a digital one on order (I really do find refractometers handy in the mash, and this should simplify my brewing.)  Again, don't really need it post boil, just curious.

Try that new one once you'll get it. I'm pretty sure you'll get much better results. I suspect that your refractometer is faulty such great deviation is simply not physically possible if the instrument and its use is ok.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on April 24, 2018, 01:57:17 PM
Thanks.  Sorry to drag this back up.  (The optical does function usefully in the mash, though, but only when I create a specific correction factor for each batch.  I suppose that supports your assessment of its accuracy.)
Title: Re: Improved Refractometer Correction calculator
Post by: Petr on April 24, 2018, 02:30:22 PM
Thanks.  Sorry to drag this back up.  (The optical does function usefully in the mash, though, but only when I create a specific correction factor for each batch.  I suppose that supports your assessment of its accuracy.)

No problem. I guess it does support that. Wort correction factor should be characteristic of the instrument, not each batch.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on April 24, 2018, 02:57:08 PM
Thanks.  Sorry to drag this back up.  (The optical does function usefully in the mash, though, but only when I create a specific correction factor for each batch.  I suppose that supports your assessment of its accuracy.)

No problem. I guess it does support that. Wort correction factor should be characteristic of the instrument, not each batch.
But it is at least simple to create specific ones.  I just note WRI at each stage of mash and boil, take a saccharometer and refractometer reading on chilled wort, and work backwards to correct the earlier readings.  These could all be compiled to come up with a single,  instrument-specific number, but as I take all these measurements anyway, it's simple and gives me a tool for tracking the progress of the mash, batch to batch, under different conditions. I'll be more interested in coming up with a single conversion factor on the digital instrument, so I'll be able to quickly and easily get an actual density reading on the fly.  Thanks again for your help.
Title: Re: Improved Refractometer Correction calculator
Post by: dmtaylor on July 17, 2018, 12:04:42 AM
The "Old Cubic" and Novotny formulae continue to be pretty much dead-nuts bulleye for me almost every time, only one odd outlier so far out of five batches.  My own refract vs. hydro data thus far:

(https://farm5.staticflickr.com/4711/25209707127_a6e1827634_b.jpg)

You can hopefully see a very light thin line diagonally from lower left to upper right -- that is the "goal line".  Goal is to be right on that line.

Bringing back from the dead...

Just a quick note to let you guys know that 3 additional data points since February also fall directly on the diagonal line for the Novotny Linear formula, and the one Terrill calls "Old Cubic".  I'm sold.  I feel very comfortable using my refractometer for FG readings whenever I want, always accurate within 0.001 which I'd say is good enough.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on July 17, 2018, 12:32:47 AM
I'll join the zombies.... Petr was right about my results improving with my digital refractometer.   I've been using it long enough to conclude that its correction factor is effectively nonexistent,  1.00, with any apparent discrepancy with saccharometer readings attributable to the vagaries of eyeballing a thing floating in turbid, bubbly liquid. I am now confidently using mine throughout the process from mash to FG.  I'm using the BF calculator which uses the Novotný cubic I believe, but this and the two Dave mentions all converge pretty closely and all, as Dave says, "close enough."  In fact, I'd go along with "dead nuts."
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on July 17, 2018, 12:46:44 AM
I'll join the zombies.... Petr was right about my results improving with my digital refractometer.   I've been using it long enough to conclude that its correction factor is effectively nonexistent,  1.00, with any apparent discrepancy with saccharometer readings attributable to the vagaries of eyeballing a thing floating in turbid, bubbly liquid. I am now confidently using mine throughout the process from mash to FG.  I'm using the BF calculator which uses the Novotný cubic I believe, but this and the two Dave mentions all converge pretty closely and all, as Dave says, "close enough."  In fact, I'd go along with "dead nuts."

I’ve recently received a Speidel Braumeister 20L so I’m back to just using a hydrometer post brewday to take readings.
Title: Re: Improved Refractometer Correction calculator
Post by: Robert on July 17, 2018, 01:09:37 AM
I'll join the zombies.... Petr was right about my results improving with my digital refractometer.   I've been using it long enough to conclude that its correction factor is effectively nonexistent,  1.00, with any apparent discrepancy with saccharometer readings attributable to the vagaries of eyeballing a thing floating in turbid, bubbly liquid. I am now confidently using mine throughout the process from mash to FG.  I'm using the BF calculator which uses the Novotný cubic I believe, but this and the two Dave mentions all converge pretty closely and all, as Dave says, "close enough."  In fact, I'd go along with "dead nuts."

I’ve recently received a Speidel Braumeister 20L so I’m back to just using a hydrometer post brewday to take readings.
Oh, I have the brew length to pull 200mL saccharometer samples all I want.  I actually find the digital refractometer terribly convenient and probably (now I have the system shaken down) more reliable than the combination of saccharometer, eyeball, and a sample with suspended matter and upwelling bubbles.  (Anything that takes me out of the equation is probably an improvement...  ;D )
Title: Re: Improved Refractometer Correction calculator
Post by: Big Monk on July 17, 2018, 03:16:51 AM
I'll join the zombies.... Petr was right about my results improving with my digital refractometer.   I've been using it long enough to conclude that its correction factor is effectively nonexistent,  1.00, with any apparent discrepancy with saccharometer readings attributable to the vagaries of eyeballing a thing floating in turbid, bubbly liquid. I am now confidently using mine throughout the process from mash to FG.  I'm using the BF calculator which uses the Novotný cubic I believe, but this and the two Dave mentions all converge pretty closely and all, as Dave says, "close enough."  In fact, I'd go along with "dead nuts."

I’ve recently received a Speidel Braumeister 20L so I’m back to just using a hydrometer post brewday to take readings.
Oh, I have the brew length to pull 200mL saccharometer samples all I want.  I actually find the digital refractometer terribly convenient and probably (now I have the system shaken down) more reliable than the combination of saccharometer, eyeball, and a sample with suspended matter and upwelling bubbles.  (Anything that takes me out of the equation is probably an improvement...  ;D )

My handheld refractometer is great for brewday measurements.
Title: Re: Improved Refractometer Correction calculator
Post by: WhiteHausBrews on August 07, 2018, 05:53:04 AM
Had to created a forum profile just so I could say thank you all for this thread. It has been tremendously informative and after switching from hydro to refract cold turkey a few brews ago it has really hit home that I should probably do a few comparisons at least to get my correction factor dialed in.

Looking forward to finding more rabbit holes to dive down here. Thanks again!