From: Ryuji Suzuki (rs@silvergrain.org)
Date: 10/28/03-11:16:29 PM Z
From: Liam Lawless <liam.lawless@blueyonder.co.uk>
Subject: RE: Test for Silver Metal in Print?
Date: Wed, 29 Oct 2003 03:17:22 +0000
> I recall from somewhere that toning (with gold, at any rate) results in
> the partial replacement of silver, this silver being converted to the
> chloride (taking Cl from the gold chloride) as gold deposition takes
> place, and that this is one reason why prints should be fixed after Au
> toning.
I don't know which gold toner you are talking about, but metallic
silver does not react with chloride ions to make silver chloride.
(You can understand this from electrochemistry chapter of freshman
chem book, but think about it - if it could, no one would use a silver
spoon to have a cup of onion soup!!)
In bleaching baths, there needs to be another oxidizing agent that
deprives electron from metallic silver before forming silver halide
crystals due to bromide or chloride in the solution. Potassium
hexacyanoferrate (III) (aka potassium ferricyanide) is one example.
-- Ryuji Suzuki "Reality has always had too many heads." (Bob Dylan, Cold Irons Bound, 1997)
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