Author Topic: SG/Brix refractometer completely useless?  (Read 2478 times)

Offline enso

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SG/Brix refractometer completely useless?
« on: April 27, 2011, 01:02:45 PM »
So I asked for one of these for my birthday only to now read in another thread that these do not work.  Are they completely useless or can I read the brix side of the scale and get an accurate reading?
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Offline glastctbrew

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Re: SG/Brix refractometer completely useless?
« Reply #1 on: April 27, 2011, 01:19:56 PM »
So I asked for one of these for my birthday only to now read in another thread that these do not work.  Are they completely useless or can I read the brix side of the scale and get an accurate reading?

I love my refractometer and couldn't imagine brewing with out it, I just completely ignore the SG scale.  I use Sean Terrill's spreadsheet to convert Brix to SG.  http://seanterrill.com/2011/04/07/refractometer-fg-results/  There is a spreadsheet link about 2/3rds of the way down page.
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Offline enso

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Re: SG/Brix refractometer completely useless?
« Reply #2 on: April 27, 2011, 01:22:21 PM »
So you have one that has SG and Brix then?  So long as the brix side works I will be glad.
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Offline tom

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Re: SG/Brix refractometer completely useless?
« Reply #3 on: April 27, 2011, 01:25:14 PM »
Once fermentation starts, the alcohol will mess with the reading.  You can just use a hydrometer or there are some correcting formulae you can plug into.  Check out Sean Terrill's site for more info on that.
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Offline enso

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Re: SG/Brix refractometer completely useless?
« Reply #4 on: April 27, 2011, 01:28:46 PM »
Yes I am aware of the alcohol issue.  I plan to only use it preboil and maybe during the boil.  What I am asking about is some folks have said the refractometers that have a dual S.G. and Brix scale do not work.  I was wondering if that meant it is completely useless or just the S.G. side is inaccurate.
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Offline glastctbrew

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Re: SG/Brix refractometer completely useless?
« Reply #5 on: April 27, 2011, 01:41:14 PM »
So you have one that has SG and Brix then?  So long as the brix side works I will be glad.

Yep, mine has Brix on left and SG on right side of the display.
Scott
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Offline Slowbrew

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Re: SG/Brix refractometer completely useless?
« Reply #6 on: April 27, 2011, 02:30:25 PM »
I have heard the SG scale is not very accurate but I cannot speak from experience.  My refractometer is Brix only and I love the ease of using it.

As for only using it for the pre-fermentation side of brewing I suggest you use it for readings during and after fermentation too.  I use a spreadsheet I downloaded from MoreBeer to do the conversion after there is alcohol in solution and it is dead on accurate.  You only need 2 values for it to do the calculation.  You need the reading (in Brix) of your OG and your current gravity ready (again in Brix) and it spits out you answer in Specific Gravity.

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Offline hopfenundmalz

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Re: SG/Brix refractometer completely useless?
« Reply #7 on: April 27, 2011, 02:37:39 PM »
Man, you shouldn't have told me it was useless!  All those beers over the last 5 years were crap then, and the awards were bogus.

Tell me what forum says this?

Seriously, you just have to understand the tool and use it properly.  Promash has both Brix and SG when you formulate the recipe.  You get used to looking at both and switching back and forth.  The morebeer converter is good for the FG.  I have been using a refractometer for so long, I would not go back to a hydrometer on the hot side.

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Offline a10t2

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Re: SG/Brix refractometer completely useless?
« Reply #8 on: April 27, 2011, 03:09:51 PM »
I think I'm the one who started this...

With the caveat that I've never actually used one of these and and am working entirely from the pictures I've seen online, yes, the SG scale is inaccurate. The manufacturer appears to have used the "multiply by four" rule, rather than an actual Brix-to-SG conversion. So the Brix scale should be just as accurate as any other refractometer, but the SG scale will only be within one "point" up to about 1.050. As far as I know, the Brix scale is still a pure sucrose measurement, so you'll need to apply a correction factor when measuring wort.

This post has some general information on how to use a refractometer, as does the September 2, 2010 episode of Basic Brewing Radio: http://seanterrill.com/2010/06/11/refractometer-estimates-of-final-gravity/

For FG estimation, I have a recently updated spreadsheet, which glastctbrew linked to earlier: http://seanterrill.com/2011/04/07/refractometer-fg-results/

This *should* give better results than the MoreBeer/ProMash/BeerSmith/what have you formula, although that's also included so that people can verify it for themselves.
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Offline weithman5

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Re: SG/Brix refractometer completely useless?
« Reply #9 on: April 27, 2011, 03:58:14 PM »
I have a couple of apps for my iphone that both convert brix to sg with numbers the same as every conversion graph, spreadsheet i have seen.  simple enough at high og to add a point or two based on experience.  free apps by the way.
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Offline enso

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Re: SG/Brix refractometer completely useless?
« Reply #10 on: April 28, 2011, 05:21:10 AM »
...free apps by the way.

Nice!  Now, you got a free iphone and a prepaid subscription to use it for me as well!  Oh, and we could use some cell service up here also...   ;D

Okay thanks folks.  Cant wait to play with it...  That's assuming I actually get what I asked for!   :D
Dave Brush

Offline oscarvan

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Re: SG/Brix refractometer completely useless?
« Reply #11 on: April 28, 2011, 01:35:40 PM »
OK Lucy..... 'splain to me why the same instrument is accurate on the Brix scale and not on the SG scale..... ???
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Offline Kit B

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Re: SG/Brix refractometer completely useless?
« Reply #12 on: April 28, 2011, 01:59:52 PM »
I have my doubts as to whether this issue is valid.
I mean...I'm sure there are some bogus products that are being made.
But, my buddy has one that seems quite valid.

Another friend & I have an ongoing debate about Brix vs SG.
He claims that it's impossible to have an ATC refractometer measure both.
I totally disagree.
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Offline glastctbrew

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Re: SG/Brix refractometer completely useless?
« Reply #13 on: April 28, 2011, 02:00:30 PM »
OK Lucy..... 'splain to me why the same instrument is accurate on the Brix scale and not on the SG scale..... ???

My guess, The instrument is designed for reporting brix.  To make it more appealing to home brewers and vintners they added an SG to one side of the scale.  Sounds great but whoever setup the printing of the scale used a faulty correlation factor.  It COULD read SG accurately but the SG scale in the display is off.
Scott
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Offline denny

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Re: SG/Brix refractometer completely useless?
« Reply #14 on: April 28, 2011, 02:05:28 PM »
He claims that it's impossible to have an ATC refractometer measure both.

What's his reasoning?
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