Work out percentage alcohol (please help)

What I use is:

1.080 - .992= .088 X 131.25= 11.5% I don't know if it the right way but it works for me, any comments...

I believe the "certain figure" you are looking for is 0.736

So 1.08 - 0.992 = 0.088 / .736 = .1196 or 11.96% alcohol.

-- Robert J. Romano, CPA

That's a bit more optimistic than my hydrometer's scale, which puts the potential alcohol at ~10.3%.

A lot depends on fermentation rate. Some depends on the yeat's conversion efficiency. Ambient temperature certainly plays a role, as do container size and composition.

The only way to be sure is to measure it after it goes dry.

Tom S

And for that you need a vinometer.

-- Robert J. Romano, CPA

There are other ways. One involves measuring the specific gravity with a narrow range hydrometer, boiling a precisely known volume down to drive off the alcohol, adding back water to the initial volume, remeasuring the specific gravity and calculating the alcohol from the difference in S.G. readings.

There's also an enzyme test IIRC, but you'd need to get a commercial lab (e.g. Vinquiry) to do that for you. That'd set you back ~$20.

Tom S

11.25% is what you got.

I did a math error. I just looked at my hydrometer, and it now looks like a more correct firgure is in the 11.6% range, a very good finish!

Every time I look at my &$#@! hydrometer, I come up with a different figure. I guess my nightly meds are kicking in... It seems that the 0.992 cannot be subtracted from 1.080 to show a drop in sugar indicating .088 sugar going to alcohol, so, my THIRD and FINAL answer is, he started with a potential of 1.080 or 10.3%, and has achieved it.

Yes, temps play a role, and somewhere somehow I LOST the blasted conversion table that came with my hydrometer. AAARRGGHHHH!!!!!! Container size and composition play no role in determining sg at all.

0.992 looks pretty darn dry to me! I've never gotten below about 1.020, but then I love my wine sweet; it's a holdover from my hippie daze of Boone's Farm!!! LOL!!! I'll start with an sg of 1.130......... :-)

Those are notoriously finicky and inaccurate. I just use my hydrometer, and my now AWOL temp conversion chart.

I didn't mean to imply that they did. What I meant was that a larger fermenter will run hotter during fermentation and burn off more of the alcohol via evaporation, resulting in an apparently lower conversion efficiency. Same goes for a well insulated fermenter as opposed to one that is not.

Tom S

Hi Matt, Louise, Robert, et al.

You can not have more alcohol in the wine than your original PA predicts. Both my hydrometer and chart indicate this is ~10.6%ABV.

If a wine finishes dry, there is *no need* for an end alcohol calculation since the original PA already tells you how much alcohol is in that wine.

If a wine "sticks" and the maker decides to "restart" and force it to go dry, then the same thing applies. Since it ends up dry, the original PA tells you how much alcohol is present.

Only if a ferment ends with residual sugar present is there a need for end alcohol and residual sugar calculations since part of the sugar is _not_ consumed and thus converted to alcohol. In this case the alcohol will be _less_ than the original PA predicted.

Keep in mind that _part_ of the total SG drop is caused by the effects of the alcohol on our _end_SG reading, so _total_drop cannot be used to make such calculations. Only the amount of drop caused by the consumption of fermentables (sugars) can be used to estimate end alcohol. HTMS

Frederick

Hi Louise

To get this calculation to work I would subtract 8G (8 gravity points) from the total drop to compensate for the effects of the alcohol on the end reading. Thus giving:

1.080 - 0.992 = 0.088 0.088 - 0.008 = 0.080 0.080 x 131.25 = 10.5%ABV

Frederick

Hi Robert

To get this calculation to work I would either subtract 10G (10 gravity points) from the total drop - OR - I would subtract 8G and use a factor of 0.756 (v 0.736) thus giving:

1.080 - 0.992 = 0.088 0.088 - 0.008 = 0.080 0.080 / 0.756 = 0.1058 = 10.58%ABV

HTMS

Frederick

Right !! Except both my hydrometer and chart indicate 10.6%. But, like myself, both are very old. Guess I will have to take a look at a new hydrometer the next time I go to the store. ;o)

Not many folks seem to do these "old fashioned" RS ferments any more. (at least not intentionally). Good to know there are still a few of us around.

Frederick

Gosh - this does sound complicated!! CJJ Berry in his excellent book, 'First Steps in Winemaking,' has done all the hard work for you!

Unfortunately, the formula that CJJ Berry gives in that book is_wrong_ !! It is one of the very few mistakes that Berry made. In the copy I have, if you look on page 78 in para 3 you will find "...Say you decide to make a wine of 12 per cent alcohol. The table shows that you will require an initial SG of 1.090,...". This is true. BUT - assume that this wine ferments dry with an end SG of 0.990, and then try to use the formula given at the bottom of that same page. His formula will_try_to tell you that you will get 13.58%ABV in that wine. Obviously a mistake. You can't have it both ways, it's one or the other !! HTMS

Frederick

Yes, very true, that is why beer vats are continuously cooled.

DRAT!! THat leaves me with nothing to live off of except food and water!

resulting in an apparently lower conversion

I got a 16 gallon primary, but chickened out on using it. I've stuck with my 5 and 6.5 gallon carboys. Anybody here ever use a 16 gallon (or larger) plastic primary???? It's ported for an airlock and for filling up too. Bob<

Far out, man.... :-) I just don't like drinking dry wine that smells and tastes like paint thinner.... My 1st wife was a multimillionaire (used to own this

) and I spent my late teen years (we split when I was 20) drinking an awful lot of wine that was horrid. $150/bottle for a stomachache, no thanks pal. I loved the Mouton-Cadets of the '70's, but the rest was nasty.... Bob<

The point none of us have thought to mention is that it is alcohol by VOLUME and alcohol has an entirely different specific gravity than water does. It will go negative when it's dry, but that doesn't add to the original PA reading. I do so much better in the afternoon before I take my meds at night! LOL!!!