From: e n (emanmb@yahoo.com)
Date: 09/04/00-02:54:09 PM Z
--- Gumprint@aol.com wrote:
> Greetings. I am about to make some van dykes after
> having not made any for
> many years. The silver nitrate solution is pretty
> murky, should it be
> strained through cheese cloth or something else or
> just used as is?
After having floated sheets of paper with organic
materials on it such as albumen or gelatin, the silver
nitrate solution will get rather dark and also if
exposed to light.
If this is a light issue there may not be a "cure" but
from the organic compound contamination, you need 15
gms.of Kaolin powder per liter, (yes the main
ingredient in KeopectateŽ) stir it around in the
silver nitrate solution and let it settle overnight.
This will effectively remove the dark discoloration.
I use a siphoning set-up as illustrated in Reilly's
book to get the silver nitrate into the silvering
tray.
The Kaolin can be left in the storage bottle
indefinitely until it is no longer effective in
clearing the solution. Filtering may not be a bad
idea before and after this treatment.
eric nelson
http://www.geocities.com/emanmb/ENelson.html
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