[alt-photo] Re: Coating Silver Chloride - Non-Gelatin Based?

[Francesco Fragomeni]

Etienne,

As usual, thank you!! :)

-Francesco

Sent from my iPhone

On May 15, 2012, at 1:34 PM, etienne garbaux <photographeur at nerdshack.com> wrote:

> Francesco wrote:
> 
>> 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.
> 
> Best regards,
> 
> etienne
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