"Clyde Gill" > wrote in message
om...
> The level of pH when tartrates are forming is a factor for how
> much it will change. The further away from the wines pKa (typcially
> around 3.65) the more dramatic the change.

Hi, Clyde -
On another NG we had a similar discussion on the effect of cold stabilizing
wines. IIRC, the pKa for potassium bitartrate mentioned was a lot lower
than 3.65. It was more like 3.2 - and this data was from an organic
chemist, who certainly should be a reliable source.

> Sulfites at these elevated pH's is
> virtually useless.

I wouldn't go so far as to say that, but it's true that it takes a good deal
more free SO2 to maintain 0.8 ppm molecular SO2 at pH 3.8 than it does at
3.2.

Tom S