Sidthesquid
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Hi guys is it possible to measure the alcohol content of my homebrew without an original gravity reading? ? I forgot to measure at the start 😣
% of alcohol
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If your doing an extract kit, I would just use the OG that came with the directions.
GASoline71
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What recipe or kit did you use?
Gary
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Sidthesquid
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The problem I have is I knocked over the fv losing some of the can also reduced the water content a little
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Sidthesquid
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John bull ipa gary
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Sidthesquid
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Thanks chaps it does taste great tho so happy days 😀😀
Gnomebrewer
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You can estimate OG and ABV, by measuring current gravity with both a refractometer and hydrometer (the refractometer reading will be affected by the alcohol, which makes it possible to estimate how much alcohol there is knowing that the hydrometer reading is true). But like others said, there's no real need to bother.
Morrey
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You can plug your recipe in a program such as Beer Smith and it will tell you all you wish to find out.
Yeah you can get close with the #'s and the recipe, but I see you asked is there a way or is it possible to "measure".... No not really. Not without sending it off to a lab.
Cheers
Jay
Cheers
Jay
Gnomebrewer
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Yes you can, if you have the 'correct' gravity reading from a hydrometer and the 'skewed by alcohol' gravity reading from a refractometer. An algorithm for calculating the skew for gravity readings with a refractometer reading can be reversed to give the current ABV, and subsequent OG. There is an error margin of a few gravity points though.
Teach me please. Sounds interesting and VERY worthwhile. I would LOVE to know how to do that without an OG as we get asked ALL the time in the store. I am sure there are PLENTY of people here that can benefit from this info..
Cheers
Jay
Norselord
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You could send your sample out to a lab and have them run it through a mass spectrometer or gas chromatography machine and they could give you an idea of the amount of EtOH you have in your sample.
Or you could very accurately measure out 10.00 grams of your liquid, heat your sample up to 79degrees celsius (assuming you are at or near sea level), hold it at that temp for about 15-30 minutes agitating it as best as possible, then very accurately weigh your sample again. Subtract your 10.00 gram reading from your final reading and that will tell you how much alcohol you boiled off by weight. Then multiply that number by 1.25 to convert ABW to ABV.
Alternately, you could ask yourself how important ABV is to your beer tasting experience.
P.S. you want to measure your OG moving forward.
Or you could very accurately measure out 10.00 grams of your liquid, heat your sample up to 79degrees celsius (assuming you are at or near sea level), hold it at that temp for about 15-30 minutes agitating it as best as possible, then very accurately weigh your sample again. Subtract your 10.00 gram reading from your final reading and that will tell you how much alcohol you boiled off by weight. Then multiply that number by 1.25 to convert ABW to ABV.
Alternately, you could ask yourself how important ABV is to your beer tasting experience.
P.S. you want to measure your OG moving forward.
Gnomebrewer
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OK. I'm going to use this calculator
http://onebeer.net/refractometer.shtml
There are others, but this one has worked well for me. It's designed to work out the true FG and ABV when using a refractometer (that's what I use it for), but by working backwards it can estimate OG when you have both both refractometer and hydrometer final gravity readings.
So, I have an APA in fermenter at the moment. It is currently sitting at 7.2 brix according to the refractometer (note that the refractometer measurement needs to be in brix; there's a conversion calculator at the top of the page for brix to gravity) and 1.012 according to the hydrometer. Put '7.2' into the 'Enter Final Brix' box. That doesn't get changed. Put a value into the 'Enter Original Brix' box (a guess to start with) and press calculate. If the final gravity calculation is below 1.012, the 'guess' for original brix needs to be lower (then press calculate again); if the final gravity calculation is higher than 1.012, the 'guess' for original brix needs to be increased. Keep going by trial and error until the final gravity calculation is 1.012 - in this case OG = 13.5 brix = 1.056 (the actual OG, which I measured at the time, was 1.054).
Gnomebrewer
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A good idea, but this wouldn't work. Although the boiling point of ethanol is 78C, a mixture containing ethanol and water won't boil until much warmer than 78C and comes off as a mixture, not as pure ethanol. So, at 79C you'd get very little evaporation and what did evaporate would be well below 100% ethanol. With your method (at a warmer temp), you'd need to also catch the distillate and measure the alcohol content with an alcoholmeter, but then you'd be distilling which is illegal in most places.
Norselord
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If you have a very accurate thermometer and you assume an ideal mixture of ethanol and water, you could just measure the boiling point of the mixture - which would tell you the %ABW.
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Sidthesquid
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Thanks for all your help 👍👍
ChemErik
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If you do this, look for the initial boiling point. That is the temperature when you first see boiling. The composition will change as it boils and the temperature will increase as you get less and less alcohol.
