I have a few questions about how to use potassium carbonate or
bicarbonate to reduce acidity.

1) I read about the method of neutralizing all the acid in a portion of
the batch and then mixing that with the rest. The purpose is (I think)
to neutralize tartaric and some malic acid instead of only tartaric,
because malic will be neutralized only when all the tartatic is gone.
The question is: does this technique also apply to pottasium carbonate
or is it only for calcium carbonate?

2) After you add pottasium carbonate you need to chill the wine. How
long do you need to chill it for? One day, one month?

3) How cold does it need to get?

4) After the wine has been chilled and the tartrate salt has dropped to
the bottom, do you need to rack the wine while it's still cold so that
the salt doesn't get back in solution, or does the salt stay there even
if the wine warms back up?

5) Other than adding the pottasium carbonate, chilling, and racking, is
there anything else that needs to be done or is the process complete at
that point?

Thanks in advance.

Oh, I forgot. One other question:

7) If this process produces CO2, then after the chilling and the
racking do you need to bulk age the wine for several more months so
that the CO2 will come out?

It's funny- I'm just about to do this with one of my wines to
experiment with where I like the acidity after a MLF. If I may quote
Bill Frazier (and my apologies-)
>-
If your wine has too much acid you can raise the pH by getting rid of
some
of the acid. Try a good, hard cold conditioning first to drop some
tartaric. This may get the pH up a little. If you've already cold
conditioned the wine you can add K bicarbonate. Adding 0.9 grams/liter
will
lower acid by 0.1% or 1.0 gram/liter. I do this sometimes. There is
no
correlation between acid removed and pH increase. I calculate how
much
acid I want to neutralize (A Cab would be nice with about 0.6% acid).
I
weigh the required amount of K bicarbonate. I stick a pH probe in the
wine
(this is done in a large, open vat because there is a lot of foam
produced).
I add the K bicarbonate slowly, with gentle mixing, keeping my eye on
pH. I
may not need to add all the K bicarbonate I weighed. K bitartrate is
produced in this reaction. It's best to cold condition the wine after
to
precipitate out excess K bitartrate. This completes the acid lowering
process. You will notice a "salty" taste in the wine immediately after
treatment but this fades with time.
>-

The crystals should stay solid- they don't readily re-dissolve- at
least I've kept mine from last year as seeds with liquid on them and
they're still around

The double salt method is used with calcium carbonate, I have never
heard of using it with potassium bicarbonate. You want to get it as
cold as possible. 25 F is what I shoot for. If you can't get that cold
it will just take longer. I usually chill it for 2 to 3 weeks, if you
use some potassium bitartrate as seed crystals you can reduce that
time. If you do that you need to stir it a few times.

If you rack cold don't splash, wine picks up oxygen better at cold
temps. You can let it warm up, very little if any acid will be
reabsorbed.

You should degas by stirring.

Joe

Thanks Joe. Are you a home or commercial winemaker?

Home. My background is measurement and control so I read a lot and
approach things technically.

Aren't you in Texas? I'm working in Amarillo right now if you are
anywhere near there. (Not that anything is near anything in Texas... )

Joe

Haha, you are right. I live in Austin, which is "only" 500 miles from
Amarillo.

Great town, Austin. We have a robot there too at Seton, I've been
there.

You will fix this. More often than not the wine I thought was awful
turned out to be the best of that year because i fiddled with it.

Joe