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04-23-2012, 12:09 PM   #1
robertandrews
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Oct 2011
Cardiff, UK
Posts: 28

Start:

End:

04-23-2012, 12:40 PM   #2
beergolf

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Jan 2011
collingswood, nj
Posts: 5,878
Liked 1145 Times on 778 Posts

You are reading the wrong scale on the hydrometer.

Then your ABV is (OG-FG) X 131.25

04-23-2012, 12:56 PM   #3
IrregularPulse
Hobby Collector

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Nov 2007
Posts: 50,598
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http://www.homebrewing.org/How-to-Re...r_ep_46-1.html
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04-23-2012, 12:57 PM   #4
robertandrews
Recipes

Oct 2011
Cardiff, UK
Posts: 28

Got it. 1.052 - 1.020 x 131.25 = 4.2% abv.
That's good. I feared I had lower than that.
Thanks!

04-23-2012, 01:45 PM   #5
Blackmuse
Recipes

Mar 2012
Milton Mills, New Hampshire
Posts: 106

Beergolf gave you great advise. However, I don't believe that what you were reading is the "wrong scale" - according to those readings your abv would be just shy of 5% - first reading looks to be about 7% and the second looks to be just over 2% lets say 2.25... So, 7% - 2.25% = 4.75%.

If your first picture didn't have the bubbles we may see that it didn't quite hit 7% and you would actually be closer to what you got via the OG/FG math. (I actually prefer the OG/FG math as I find it more accurate - lot of guess work with the ABV scale).

Someone correct me if I am wrong with that observation.

04-23-2012, 02:06 PM   #6
zeg
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Jan 2012
West Lafayette, IN
Posts: 1,216
Liked 129 Times on 111 Posts

You are correct. In the first one, I'd suggest spinning the hydrometer a few times and letting it sit until the foam dissipates. The potential alcohol scale is intended for doing this calculation without "advanced math" (i.e., multiplication). It does assume that you have the sample at the same temperature for each reading, though. It's easier to find the corrections for SG (though it should just be a scale by 131 to convert that to a potential alcohol reading).

All the scales on a hydrometer are linear, so it's just a simple conversion to go from one to the other. There's no "wrong" one to read, you just have to know what to do with each number. You can always fairly trivially convert one to another (or just look at the hydrometer and use it to do the conversion for you).

04-23-2012, 04:02 PM   #7
robertandrews
Recipes

Oct 2011
Cardiff, UK
Posts: 28

Thanks. I thought the % scale was viable. Same method (subtract FG from OG), right? I read across from the % markers to gravity markers.

04-23-2012, 04:23 PM   #8
amandabab
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Mar 2012
spokane, wa
Posts: 1,971
Liked 241 Times on 183 Posts

Quote:
 Originally Posted by robertandrews Thanks. I thought the % scale was viable.
In a pure simple sugar solution it is, with beer it isn't.
Even then its alcohol potential of the solution.