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.