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Re: Extravagatype and Na2
Erich Camerling wrote:
> ... Sodium Chloroplatinate ( Na2PtCl6 , shortened Na2 ) as a contrast
> agent in standard Pt/Pd printing ...
> But when I mix ( for instance ) 3 drops Ammonium Ferric Oxalate
> ( 40g/100 ml H2O ) with 2 drops K2PtCl4 ( 20g/100 ml H2O ) and 1 dro
> Na2 ( 20g/100 ml > H2O ) I immediately get a sediment ( yellow , I
> suppose K2PtCl6 ( nearly > unsoluble ))
> Richard wrote me that I was the first who mentioned this problem.
> Other alt-photo-list members wrote about Na2 in PALLADIUM printing.
> Has anyone of this group tried Na2 in Extravagatype ? And what was the
> result ? I'm very interested.
Your problem is that K2PtCl6 is only very slightly soluble in water.
The metal double salt Richard wrote about for use to control contrast is
Na2PtCl6. These are very different.
The yellow sediment and insolubility in water are a good indication that
you did have K2PtCl6. K2PtCl6 can also be found as an impurity in
K2PtCl4 (the double salt typically used for platinum printing). The
best ways to avoid K2PtCl6 is to have a good manufacturer or source of
the material and to not store or use it at temperatures in excess of
140F, especially in the presence of sodium.
--
Jeffrey D. Mathias
http://home.att.net/~jeffrey.d.mathias/