>Another interesting question for the chemists out there is if any other
>salts would work. When I mix the palladium solution, I use KCl instead
>of NaCl because the Na in combination with heat causes the K2PtCl4 to
>convert into K2PtCl6 resulting in black specks in the print. (I use
>both platinum and palladium together.) If you would like formulas
>E-mail me direct at jeffrey.d.mathias@worldnet.att.net. A word of
>caution is that some other salts may be hazardous to work with. An
>interesting ion used with the platinum process, that I've read about in
>old literature on the subject, is ammonia, although I have never worked
>with this nor seen any results.
The only way I can see this happening is if you had enough heat to
dissassociate the Na from the Cl so that you could could get 2 more Cl for
the K2PtCl6. Since NaCl decomposes at 482 Deg. C, you've got to have a hell
of a drying cabinet for this to happen.(Pot. Chloroplatinate a insoluble
yellow powder) K2PtCl6 does not in my opinion make black specks in prints.
Black specs are most commonly caused by ferrous particles (iron or steel)
getting imbedded in the paper. This either in manufacture or after the fact.
The particles can be microscopic and make pretty nice dots. One common
source of particles is cutting paper with a razor knife and a steel rule.
The knife shaves tiny particles off the rule. Self sharpening rotary or
blade cutters are another source.
Mike Ware's Pt POP method uses Ammonium chloroplatinite. Ammonium
chloropalladite makes a nice substitute for the sodium version and produces
a slightly better black and colder tones in palladium printing. B&S will
shortly be providing both of these to the trade.
Dick Sullivan
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