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General Category => All Grain Brewing => Topic started by: psuskp on August 18, 2011, 01:54:04 PM

Title: Refractometer
Post by: psuskp on August 18, 2011, 01:54:04 PM
I broke my hydrometer (again), and I was thinking of replacing it with a refractometer. Is it worth it? There seems to be a wide range of prices. How much do I need to spend?
Title: Re: Refractometer
Post by: Slowbrew on August 18, 2011, 02:06:12 PM
I got one on eBay for $50 or so. 

I really like the convenience of using a refractometer.  Make sure your get one that is ATC.  Automatic Temp Compensation (I think that's what it stands for) allows you to use the refractometer through out a range of air temps.  It does not have to do with wort temp so make sure to let your sample cool a bit before taking a reading. 

There are good conversion spreadsheets on the web that allow you to take readings in any phase of the fermentation process.

Paul
Title: Re: Refractometer
Post by: blatz on August 18, 2011, 02:07:12 PM
just like the wide range of prices, you'll find a wide range of opinions of whether people like them or not.

I spent <$25 on ebay and have been using mine for years now - its great and really helps for during the brewing process readings - I can more easily take a midboil reading and know if I am on target for my planned OG or if it looks like I am going to be off, I can either fix it or adjust my hop schedule on the fly.

That to me is invaluable.

I also use it to take FG readings, but you need to use an adjustment for the alcohol in solution (Sean Terrill has a good link in his signature - screen name a10t2) or Beersmith has a good one as well.



Title: Re: Refractometer
Post by: blatz on August 18, 2011, 02:18:45 PM
I guess guys named Paul tend to think alike  ;D :D
Title: Re: Refractometer
Post by: narvin on August 18, 2011, 02:35:00 PM
I would suggest having both.  I love my refractometer, but I like to occasionally check against a hydrometer.

I use the refractometer for FG readings during and after fermentation (as well as measuring commercial beers - you can back-compute OG and FG based on the abv they advertise). It's incredibly easy to use without losing a bunch of beer.  Sean's spreadsheet is more accurate than the tools you see in ProMash or online, which always measure low in my experience.  I had previously found that adding about 0.5 brix to your reading was a rough swag that made the FG calculators a lot closer.
Title: Re: Refractometer
Post by: cenosillica on August 18, 2011, 03:57:40 PM
I would recommend having both. Your hydrometer will be able to accurately check your FG. A refractometer does not accurately read FG when there is alcohol present, you have to make a rough adjustment to compensate or find an online conversion tool. Therefore, I prefer to use a refractometer on brew day and as the fermentation progresses, I use the hydrometer. Occasionally, I use both to make sure my calibrations are in line with each tool.
Title: Re: Refractometer
Post by: bluesman on August 18, 2011, 04:41:04 PM
Another vote for both. They both have their place in the brewhouse and cellar. I use my refractometer on the front end of the process and the hydrometer for measuring gravity of finished beer. Both are a must have for me, and a worthwhile investment as well
Title: Re: Refractometer
Post by: pehlman on August 18, 2011, 10:35:55 PM
I like that concept of using the refractometer on brew day and the hydrometer on the tail end of fermentaion. I've broken a few hydrometers and I think a refractometer is going to be my next piece of equipment.
Title: Re: Refractometer
Post by: Malticulous on August 18, 2011, 11:12:02 PM
I hate mine. It always 2-10 point off from my hydrometer. It useless to me.
Title: Re: Refractometer
Post by: beerprof on August 19, 2011, 01:42:57 AM
I hate mine. It always 2-10 point off from my hydrometer. It useless to me.
Have you calibrated it? It should not be 2 - 10 points off.
Title: Re: Refractometer
Post by: tygo on August 19, 2011, 03:19:25 AM
I hate mine. It always 2-10 point off from my hydrometer. It useless to me.
Have you calibrated it? It should not be 2 - 10 points off.

+1

I had a lot of problems with getting mine to read correctly to the point where I was thinking it was a useless piece of junk.  But thanks to some help from some folks here I now have it to the point where I feel like I can rely on it (almost) as much as I do my hydrometer, at least on the hot side.

The keys for me were calibrating it before each use at the ambient temperature I was using it at, reading it on the brix scale (mine is a dual scale), and reducing the brix reading I do get by 4%.  Since I've done those things my refractometer readings and hydrometer readings usually agree to within 0.001 SG.



Title: Re: Refractometer
Post by: Malticulous on August 20, 2011, 08:21:23 PM
I calibrated it they day I got it at room temp. It was about $30 on ebay from Hong Kong.

I searched and found I'm not alone with the problem. Both the hydrometer and refractomerter or designed for sucrose. Beer is a complex blend of sugars that will refract differently.
Title: Re: Refractometer
Post by: a10t2 on August 20, 2011, 08:44:14 PM
Beer is a complex blend of sugars that will refract differently.

Granted, but with the appropriate corrections the hydrometer and refractometer should still agree within a point or two for both OG and FG. If you can't get that kind of agreement, and they've both been calibrated properly, then I'd bet one or the other is defective.
Title: Re: Refractometer
Post by: Malticulous on August 20, 2011, 08:57:54 PM
What are the appropriate corrections?
Title: Re: Refractometer
Post by: a10t2 on August 20, 2011, 09:35:18 PM
What are the appropriate corrections?

http://seanterrill.com/2010/06/11/refractometer-estimates-of-final-gravity/
http://seanterrill.com/2010/07/20/toward-a-better-refractometer-correlation/
http://seanterrill.com/2011/04/07/refractometer-fg-results/

The first post gives some basic methodology, and the most recent FG corrections are in the last post.
Title: Re: Refractometer
Post by: Malticulous on August 21, 2011, 03:24:44 PM
Thanks, but I still want to taste my FG sample.

Yesterday I brewed a cream ale. Pre-boil refractometer reading was 3 points low and OG was 5 high. I understand there a many reasons why is could have been. The hydrometer simply is a better tool. Chilling 4oz does not take too long.
Title: Re: Refractometer
Post by: a10t2 on August 21, 2011, 04:21:09 PM
The hydrometer simply is a better tool.

Agree to disagree, then. ;)
Title: Re: Refractometer
Post by: beerdoc on September 01, 2011, 03:41:10 AM
A refractometer is not really a replacement for a hydrometer. The refractometer is faster and easier for unfermented wort, especially if it is hot (it only takes a minute to cool the  tiny sample you need for the refractometer). Each percent alcohol introduces an error of 0.4 brix which comes to 1.6 SG points. So beer with 5% alcohol by weight is going to give an error of 8 points. If  the FG is 8 pts, it's going to look like 16 pts. I would not be comfortable dealing with an error of that magnitude with a correction. Corrections are fine when the effect is a lot bigger than the correction.
Title: Re: Refractometer
Post by: bluesman on September 01, 2011, 12:42:05 PM
A refractometer is not really a replacement for a hydrometer. The refractometer is faster and easier for unfermented wort, especially if it is hot (it only takes a minute to cool the  tiny sample you need for the refractometer). Each percent alcohol introduces an error of 0.4 brix which comes to 1.6 SG points. So beer with 5% alcohol by weight is going to give an error of 8 points. If  the FG is 8 pts, it's going to look like 16 pts. I would not be comfortable dealing with an error of that magnitude with a correction. Corrections are fine when the effect is a lot bigger than the correction.

Yes. I use both for this very reason. They both have their advantages and disadvantages.
Title: Re: Refractometer
Post by: gimmeales on September 01, 2011, 02:28:47 PM
A handy spreadsheet that does the corrections for you is here:  http://morebeer.com/learn_vids/vids_refract

After a couple of brews using both Refractometer and Hydrometer side-by-side (and spot checks here and there), I found the Refractometer to be dead-on and now hardly use my Hydrometer anymore.  Love the Refractometer!  (mine was one of the $25 jobs off eBay).
Title: Re: Refractometer
Post by: weithman5 on September 01, 2011, 02:45:40 PM
i liken this debate to one i have had regarding two other tools. my old chalk line and my new laser.  the laser does just about everything i need but once in a while it is nice to snap a chalk line.  i have not gotten a refractometer yet but when i do, i am sure that every now and then i will still want the hydrometer.
Title: Re: Refractometer
Post by: bo on September 01, 2011, 02:52:22 PM
i liken this debate to one i have had regarding two other tools. my old chalk line and my new laser.  the laser does just about everything i need but once in a while it is nice to snap a chalk line. 

Like when you're in very bright light.
Title: Re: Refractometer
Post by: weithman5 on September 01, 2011, 03:04:54 PM
and cutting an angle in long runs of  plywood or drywall
Title: Re: Refractometer
Post by: denny on September 01, 2011, 03:44:00 PM
A handy spreadsheet that does the corrections for you is here:  http://morebeer.com/learn_vids/vids_refract


And a much more accurate one here...

http://seanterrill.com/2011/04/07/refractometer-fg-results/
Title: Re: Refractometer
Post by: Kit B on September 02, 2011, 01:31:07 PM
I've noticed that my correctly calibrated refractometer gives different readings, with nearly every drop of the slide cover.
I have had the same sample give me more than 3 different readings, when I'm testing my boil.
In fact, a friend of mine insists on opening & closing his cover, until he likes what he sees.
I think this is possibly a bad practice...
While I understand that he's not changing sugar content, I imagine that something has to be skewing the results, if the reading is changing...My first guess is definitely temperature, but I hypothesize that temperature is not the only culprit.
A correctly made hydrometer is the more accurate beer-making tool, IMHO.
But, it's very nice to be able to get readings during the sparge or boil.
I'm just very skeptical of how folks use the refractometer.

I have recently resorted to allowing my sample-filled refractometer sit for several minutes before I read it.
This seems to alleviate any questions regarding whether or not I can trust the measurement.
Title: Re: Refractometer
Post by: bluesman on September 02, 2011, 01:46:42 PM
When using a refractometer, one must pay attention to detail and be consistent.

Sampling boiling wort can be tricky. There can be some evaporation occurring just prior to closing the cover. Any break material that makes it way into the sample can also skew the readings.

The best way to become confident with your refractometer is to take a liter of wort (68F) and measure it with a calibrated hydrometer. Then using the same wort, start taking some readings using your refractometer. Take about ten readings and compare to your hydrometer reading. You should find that the readings will be somewhat consistent to each other and close to the hydrometer reading.
Title: Re: Refractometer
Post by: bo on September 02, 2011, 01:46:54 PM
I've noticed that my correctly calibrated refractometer gives different readings, with nearly every drop of the slide cover.
I have had the same sample give me more than 3 different readings, when I'm testing my boil.
In fact, a friend of mine insists on opening & closing his cover, until he likes what he sees.
I think this is possibly a bad practice...
While I understand that he's not changing sugar content, I imagine that something has to be skewing the results, if the reading is changing...My first guess is definitely temperature, but I hypothesize that temperature is not the only culprit.
A correctly made hydrometer is the more accurate beer-making tool, IMHO.
But, it's very nice to be able to get readings during the sparge or boil.
I'm just very skeptical of how folks use the refractometer.

I have recently resorted to allowing my sample-filled refractometer sit for several minutes before I read it.
This seems to alleviate any questions regarding whether or not I can trust the measurement.

He could very well be skewing the results. By opening the cover, you allow a little evaporation to occur. that could give you a higher than normal reading. When you place that drop on the lens it should be closed immediately and I allow mine to set for about 30 seconds before taking a reading.