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Old 01-11-2010, 04:48 AM   #1
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Default ABV measurement question (post wort additions)

Hi all,

I brewed a hybrid of a few recipes I found for an IPA and I'd like to figure out the actual ABV of the final product. The thing is the recipe called for doing the normal extract procedures on brew day, and then 2 days later, adding 1/2 lb of light brown sugar (boiling it first) directly to the fermenter.

My only gravity readings are from the OG (1.062) and the FG (1.014). Going from the text book here, with temp corrections, that says it's around 6.3% ABV. Problem is that has got to be off due to changing the gravity when I added the brown sugar, right? So is there some way to find out how much it altered things?

I found this site http://www.brewheads.com/refract-getabw.php which seemed promising. But I took a brix reading that said 6.8 and the FG of 1.014 which gave me 4%. That calculation seems kind of unrealistic though given the OG/FG readings.

If there's no way to figure it out after the fact, could someone at least tell me how to get an accurate calc in the future if I end up doing something like this? Thanks!

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Old 01-11-2010, 05:37 AM   #2
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A rule of thumb is to add 10 points to the OG for every pound of adjunct sugar. Since you've added a 1/2 pound of brown sugar, I'd say you raised your OG by 5 points, going from 1.062 to 1.067.

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Old 01-11-2010, 01:27 PM   #3
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Here's a free homebrew calculator. Just enter all your ingredients and voila! All your questions answered.

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Old 01-11-2010, 03:46 PM   #4
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After the fact, you'll need a precision scale and a water bath to boil off the alcohol.
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