Re: Vandyke Variables

Sam Wang (stwang@CLEMSON.EDU)
Wed, 17 Jun 1998 09:53:09 -0400

>We'd mix up a few liters for sale and pack in 100 ml bottles and a day or
>so later they'd all have silver precipitate in the bottoms. Quite a
>nuisance, and even more so if you have shipped some to a customer. Like we
>sell it by the liter sometimes to schools. If you get the preciptiate, just
>keep slowly adding tartaric acid until it is all dissolved.
>
>You will also find that it prints better as well.
>
>
>--Dick Sullivan

Hello Dick,

I think what you mentioned here is the whitish precipitate, which I take as
undissolved silver, and which does dissolve with the addition of tartaric
acid. However, the silvery colored plated silver is a different matter; no
matter how much tartaric acid is added (I even added some ammonia), it
would not disappear. This loss of silver from the solution definitely would
not help but reduce print density, and that would explain why the freshly
mixed solution would give greater density. By the way, this happens with
both the solution from we bought from you and the ones I mixed from scratch.

Sam
Sam Wang
stwang@clemson.edu
------------------
"The virtue of the camera is not the power it has to transform the
photographer into an artist, but the impulse it gives him to keep on
looking - and looking."
- Brooks Atkinson, Once Around the Sun