Jim wrote "I'm not after n'th degrees here, just a reasonable 'likely PA' to
help me make easy decisions."
Jim, if you just want a reasonable *** prediction here's a pretty simple
approach. These equations assume a wine ferments to dryness. Even though a
hydrometer will display a negative number for a dry wine, I assume the end
point is 1.000 because you can't ferment anything that wasn't there in the
first place. And, the negative hydrometer reading for a wine at dryness is
due to the influence of ***. By using only the starting specific gravity
value there is no influence of ***. Therefore, I use the difference
between starting specific gravity and 1.000 in the calculation.
*** By Volume Calculation
Reference; "Homebrewing, Volume 1", by Al Korzonas, pg 31
og = original specific gravity
fg = final specific gravity (in the case of wine 1.000)
Calculation of *** by weight;
%ABW = (og - fg) x 105
Calculation of *** by volume;
%ABV = %ABW x 1.25
Combined method for %ABV;
%ABV = (og - fg) x 131.25
It's simple to set up the "Combined method for %ABV" equation in a
spreadsheet...then just plug in the starting specific gravity and get your
answer. All you need is a hydrometer that reads in specific gravity...no
charts, no tables.
Olathe, Kansas USA
I will indeed be after a hydrometer which matches some published
> scales at least. The SG readings make the grade thankfully for now.
> That just leaves me claculating residual sugar in my cranberry-currant
> wine which is looking dangerously high this close to transfer to secondary
> at 1060 with two days to go (out of 7 projected at 20C or so) at an
> average temperature of 21C . Damn my attempts to convert and scale up US
> Pints to UK litres from a 1 - 6 gallon (US quantities) My maths will let
> me down even ifmy hydrometer doesn't.
> As Terry Garey tells me, 'time is on your side'! A good job, since this
> newbie in the UK is wishing that they bought a triple scale hydrometer at
> the other shop... Seriously, thanks to everyone who replies as well as
> reads (and without prejudice) you help a very new winemaker to learn by
> his mistakes...
>>> I found 5 different ways PA calculations
>>> Thanks for your comments though.
>> That is a very good reference, Ben is very well informed. Those
>> references I was talking about in 'Principles and Practices of
>> Winemaking' are very similar to what Ben describes. The reason I
>> mentioned 60 years was that one of the last good references written (in
>> the US) was by Bates called Polarimetry, Saccharimetry and the Sugars
>> in 1943 or so. NIST still used that reference to calibrate hydrometers
>> last time I checked. I got a used copy (because I'm a geek and had to
>> know...) :)