Comments on: How Brewers Measure Alcohol in Beer (Part 7) http://hop-talk.com/2008/03/10/how-brewers-measure-alcohol-in-beer-part-7/ This blog is about beer and life. Fri, 25 Jul 2008 20:59:06 +0000 http://wordpress.org/?v=2.6 By: Ron http://hop-talk.com/2008/03/10/how-brewers-measure-alcohol-in-beer-part-7/#comment-8907 Ron Tue, 08 Apr 2008 12:20:21 +0000 http://hop-talk.com/2008/03/10/how-brewers-measure-alcohol-in-beer-part-7/#comment-8907 That is a neat method, and I'm sure some home brewers would even venture into it because many are more than just beer geeks (like myself). Another comment, many brewers say the SP gravity not in its decimal form; for example 1.069 would be spoken "ten sixty nine". That is a neat method, and I’m sure some home brewers would even venture into it because many are more than just beer geeks (like myself).

Another comment, many brewers say the SP gravity not in its decimal form; for example 1.069 would be spoken “ten sixty nine”.

]]> By: Calvin Perilloux http://hop-talk.com/2008/03/10/how-brewers-measure-alcohol-in-beer-part-7/#comment-8838 Calvin Perilloux Fri, 04 Apr 2008 20:51:54 +0000 http://hop-talk.com/2008/03/10/how-brewers-measure-alcohol-in-beer-part-7/#comment-8838 There's also a method to calculate the alcohol based upon the Specific Gravity of the finished beer (FG or Finishing Gravity, as brewers call it) and the Refractive Index. For this you'll need a very precise, narrow-range hydrometer, as well as a precise, calibrated refractometer. Since the alcohol in the beer tends to counteract the refraction caused by the residual sugars at a different rate than it would affect the specific gravity reading, you can use the values from these two different measurements to calculate the alcohol content. It's pretty neat, and I wish I had the formulas here; you can probably find them with enough tedious searching on the web. In any case, the hard part of this isn't just the math, which is basic algebra. It's getting the precision you need. If you're off by a small amount in your SG measurement, that can skew the final result a lot. But given the right equipment, you can easily get a value with an error of +/- 0.2% ABV or so, sometimes even closer. It's pretty cool to use this to see if beers you suspect are over-alcohol for their style indeed are too strong. But if you are able to measure the beer both before fermentation and after, then you can do a more accurate job a lot easier with your method! There’s also a method to calculate the alcohol based upon the Specific Gravity of the finished beer (FG or Finishing Gravity, as brewers call it) and the Refractive Index. For this you’ll need a very precise, narrow-range hydrometer, as well as a precise, calibrated refractometer.

Since the alcohol in the beer tends to counteract the refraction caused by the residual sugars at a different rate than it would affect the specific gravity reading, you can use the values from these two different measurements to calculate the alcohol content. It’s pretty neat, and I wish I had the formulas here; you can probably find them with enough tedious searching on the web.

In any case, the hard part of this isn’t just the math, which is basic algebra. It’s getting the precision you need. If you’re off by a small amount in your SG measurement, that can skew the final result a lot. But given the right equipment, you can easily get a value with an error of +/- 0.2% ABV or so, sometimes even closer. It’s pretty cool to use this to see if beers you suspect are over-alcohol for their style indeed are too strong.

But if you are able to measure the beer both before fermentation and after, then you can do a more accurate job a lot easier with your method!

]]> By: Helen Cole http://hop-talk.com/2008/03/10/how-brewers-measure-alcohol-in-beer-part-7/#comment-8656 Helen Cole Thu, 20 Mar 2008 00:49:29 +0000 http://hop-talk.com/2008/03/10/how-brewers-measure-alcohol-in-beer-part-7/#comment-8656 Thank you once and thank you twice for the hydrometer picture with the red line showing a reading. I'm a visual right brained person and could not figure out which set of numbers stood for which decimal place. I looked at over 50 sites. Yours is the only one with the JPG. Slán gó foille agus beannacht leat agús dó beoir. Bye for now and blessings on you and your beer. Thank you once and thank you twice for the hydrometer picture with the red line showing a reading. I’m a visual right brained person and could not figure out which set of numbers stood for which decimal place. I looked at over 50 sites. Yours is the only one with the JPG.
Slán gó foille agus beannacht leat agús dó beoir.
Bye for now and blessings on you and your beer.

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