Joe Sallustio wrote:

On Nov 26, 2:46 pm, "Paul E. Lehmann"
wrote:
Joe Sallustio wrote:

Hi. Is there a special starter I should use
to
re-start this? Room temperature shouldn't
be an issue - it's being kept in my pantry
so it is always warm enough.

Steve's post already gave you great advice
and the correct value of
'potential alcohol' for 1.100SG. (My tables
came from NBS so I know
they are right.) The only thing I would
expand on is the amount of
time to give it to get going. Starters need
to get going really well
before you add them to the total volume. I
keep doubling the volume of the starter and
let it get back to fermenting strongly.

13% ABV for an apple wine might be a little
heavy duty; if this died at around 9 or 10 %
I
might be happy with that. I show that as
1.022 to 1.029 S.G.

bobdrob,
I show 1.115 as 19.3 % ABV; I have the book
at home that probably
takes them higher; I have spreadsheet I made
on
my work PC. I can email you the spreadsheet.

Joe

Joe, are you sure of that? I quick check on my
program shows 1.115 SG to be equivalent to
15.78 Brix and the PA to be 15.78

Hi Paul,
Yes, I'm sure to a rounding error. I have the
book now. Baume
(modulus 145) is what most people refer to as
'potential alcohol'. I show 34.3 brix =1.14985
S.G. =18.90 Baume 145 at 20C.

I really think the confusion comes from two
places.

One, alcohol concentrations can be measured by
volume (V/V or ABV) or
weight ABW) . Most refer to ABV now and don't
mention ABW. ABW is about 20% lower than ABV so
maybe that is what your chart is calibrated to,
weight, not volume.

More important, the potential alcohol scale is
_exactly_ what it says
it is. It is only a crude measuurement of
potential alcohol. There in no way to measure
density changes and categorically align them to
actual alcohol content with precision. The type
and quantity of yeast
used, the temperature of fermentation and the
storage conditions all
play into final alcohol content. PA does not
consider dry extract content either, most of
which is acid and is variable to an easily
measurable degree. It can't. Wine can have a
little acetic acid and can have a whole lot,
that affects the density too.

All that said, if you make the same wines the
same way with the same materials you can
probably predict pretty well what your final
alcohol
will be. I use those values as a rough guess of
where things stand
and that is it. As I see it, this scale is
useful to monitor fermentation progress and very
little else because then is a
marginally relative measurement. Even then the
acids are changing to a measurable degree and
all my hydrometers measure is total density at a
given temperature.

As to why it doesn't go below zero, I'm pretty
sure Baume calibrated his scales with salt
solutions so by definition they can't go below
zero. The final gravity is much affected by dry
extract content so where a dry wine will end up
isn't just a matter of alcohol, it's the
acid content and other dissolved solids too.
The best relatively cheap way to measure alcohol
is by distillation and hydrometry; that
way you are measuring relatively pure
components. The best cheap way to measure
residual sugar is Clinitest tablets.

Physics is cool but I treat the PA scale like
Myth Busters; I watch it
but I don't lend a lot of weight to it...

Joe

Just curious, what does your book say the PA and
SG equivalent to 22 Brix is?

Personally, I am not hung up on Alcohol. In fact
I very much dislike the high Brix Central Valley
California wines. I much more prefer the lower
alcohol Mid Atlantic wines. They go a lot better
with food. I guess that is why they are called
"old style" wines.