Beer Forum

Looking for some input from refractometer users. I've become an expert at breaking glass hydrometers. In the last year I've gone through 6 and even broke 2 in the same brew session. So instead of buying these things in bulk (and continuing to rack wort/beer off of glass shards and tiny lead balls) I'm thinking about switching to a refractometer. But I have a concern related to sample size. Since only a few drops of wort/beer are placed on the prism, should I be concerned about samples not being representative of the entire volume? (i.e. is it safe to assume that the entire volume is homogeneous?) Is there a specific section of the beer that should be sampled (bottom, middle, top)? Or do you take multiple readings and average them?

Any other downsides?

Jeez, quit trying talk yourself out of moving into the 21st Century.

If your wort is well mixed, the sample will representative of the entire volume.

I've got one, and it makes sampling easy (provided you've mixed first), no more wine thiefs or racking into a graduated cylinder. The main downside that I've found is that it isn't good at gravity once fermentation has begun because alcohol causes changes in refracted light, so you may still have to keep a hydrometer on hand for final gravities. There are conversion calculators based on starting gravity that can account for the alcohol in the mix, but I've never used them. I just use a refractometer on brew day, and a hydrometer on kegging day. Get one on sale and you'll be glad that you did.

morebeer used to have a spreadsheet to convert post- or during-fermentation brix readins to SG but i can't find it. you need to know the OG.

here's the formula that i use

=round((1.003156-0.002318474*([OG in Brix])-0.000007775*([OG in Brix]^2)-0.000000034*([OG in Brix]^3)+0.00574*([Current Reading in Brix])+0.00003344*([Current Reading in Brix]^2)+0.000000086*([Current Reading in Brix]^3)),3)

Phil wrote:here's the formula that i use

=round((1.003156-0.002318474*([OG in Brix])-0.000007775*([OG in Brix]^2)-0.000000034*([OG in Brix]^3)+0.00574*([Current Reading in Brix])+0.00003344*([Current Reading in Brix]^2)+0.000000086*([Current Reading in Brix]^3)),3)

Yeah but what if your math is as bad as J's?

Here's a couple of tools that make it easy
http://brew.stderr.net/refractometer.html
http://www.brewheads.com/calc.php

Get one, you won't regret it!

BeerPal wrote:Jeez, quit trying talk yourself out of moving into the 21st Century.

If your wort is well mixed, the sample will representative of the entire volume.

Thanks Pal. My concern about mixing is with HSA when I check gravity of first runnings or pre-boil gravity . Though this is probably minor and can be minimized with little effort. I'll also want wait to mix the cooling wort for a reading just before pitching. (Not worried about HSA at that point).

The other inconvenience I can see is in having to carefully stir the beer in the carboys for FG readings. Will likely re-suspend some yeast, so that I'd have to wait for a day or so to rack (even if I hit my target).

Sounds like I'm probably being a bit over-analytical here and should just bite the bullet.

TapItGood wrote:

Phil wrote:here's the formula that i use

=round((1.003156-0.002318474*([OG in Brix])-0.000007775*([OG in Brix]^2)-0.000000034*([OG in Brix]^3)+0.00574*([Current Reading in Brix])+0.00003344*([Current Reading in Brix]^2)+0.000000086*([Current Reading in Brix]^3)),3)

Yeah but what if your math is as bad as J's?

Here's a couple of tools that make it easy
http://brew.stderr.net/refractometer.html
http://www.brewheads.com/calc.php

Get one, you won't regret it!

well you aren't supposed to do math. you paste that formula in a cell on a spreadsheet, and replace the variables (original and current brix) with cell references.

Phil wrote:morebeer used to have a spreadsheet to convert post- or during-fermentation brix readins to SG but i can't find it. you need to know the OG.

I thought that spreadsheet was in plato. It was a long time ago, but I think that I tested it plato vs brix and ended up with correct plato readings.