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. Refractometer FG Results « SeanTerrill.com There is a spreadsheet link about 2/3rds of the way down page.
So you have one that has SG and Brix then? So long as the brix side works I will be glad.
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.
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.
Yep, mine has Brix on left and SG on right side of the display.
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.
Paul
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.
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: Refractometer Estimates of Final Gravity « SeanTerrill.com
For FG estimation, I have a recently updated spreadsheet, which glastctbrew linked to earlier: Refractometer FG Results « SeanTerrill.com
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.
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.
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! 
OK Lucy… 'splain to me why the same instrument is accurate on the Brix scale and not on the SG scale… ???
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.
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.
What’s his reasoning?
I use refractool - what do you use?
Got it today. Seems pretty solid. Checked it with distilled and it was calibated. Tried it with a sample of birch sap I had left. Seemed to be on. Have to retake a hydrometer reading and see.
Yes the S.G. is apparently off.
For folks with the Brix only models, are they easier to read? Maybe I should return it and get the Brix only… But only if it is signifigantly easier to read. I kind of don’t want to bother with the hassle/time. In other words I want to play with my new toy now!
He absolutely will not agree that the temperature corrections for SG & Brix are in correlation with one another.
He claims that temperature adjustment cannot be done for both, at the same time.
No matter how I explain both mathematically & with real-world examples, he will not agree.
At this point, he’s probably just trying to be funny…I dunno.
Your friend is right, although he probably doesn’t know why. A refractometer can only measure the refractive index. 
OK…So, from what you’re saying…
The 2 scales represent measurements of completely different things & they should not be used on the same instruments.
When explained in that manner, it actually almost makes sense.
But, why are we ever trying to use a refractometer to measure gravity of any kind, when really it can’t truly provide us with that data, based on the refraction of light?
Is Brix a unit of measurement that is based on refraction, or is it a unit of measurement that is based on density?
I was under the impression that it was to measure liquid density of sucrose solutions.
I can somewhat agree that (with beer/wort) the refraction vs. gravity probably cannot be measured in this manner.
But, I have a hard time believing that you can predict the density of sucrose in a solution using a refractometer, yet not be able to use that same instrument to extrapolate Specific Gravity, with as much accuracy.
I don’t mean to start any arguments…I really want to learn & understand this.