[alt-photo] Re: Coating Silver Chloride - Non-Gelatin Based?
photographeur at nerdshack.com
Tue May 15 17:34:46 GMT 2012
>Can Silver Chloride and it's contrast agents
>be mixed purely in solution like Pt/Pl and coated directly to paper without
>making a gelatin emulsion like Mowrey teaches?
What you are describing is the "salt printing" process. However,
because silver chloride is essentially insoluble in water (and would
just precipitate out if you tried to mix a solution of it), one does
not mix the sensitizer and then coat it. (This is what accounts for
the fiddly part of gelatin emulsion chemistry -- getting the size(s)
of silver chloride grains that you want, suspended in the gelatin solution.)
Instead, for the salt process (very simplified), you coat the paper
with a salt solution ("salt" here being used in its generic sense,
not necessarily sodium chloride), let it dry, then float it on a
silver nitrate sensitizing bath, dry, and expose. Note that you need
to tone the image unless you are content with unattractive
low-contrast reddish-yellow prints (gold and/or Pt are the most
common toning agents -- I use gold followed by Pt to get a neutral black).
James M. Reilly wrote the definitive text: The Albumen and Salted
Paper Book (1980, ISBN 0-87992-020-3). It is available on the web.
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