From: Jeffrey D. Mathias (jeffrey.d.mathias@att.net)
Date: 03/22/03-08:39:13 PM Z
david distefano wrote:
>
> to be on the safe side, i have ordered new ferric ox. and pot. ox. i also bought
> new trays. some one made a comment about new ferric ox. and old palladium. i was
> under the impression that platinum and palladium had no shelf life problem. am i
> wrong in this assumption. if so i will also purchase new plat. and palladium.
> also i had started mixing cessium palladim with standard palladium and platinum.
> could this have been a cause of my problems. i had never done this in the past.
> i do use super actinic bulbs. they are about 2 years old everything else is the
> same.
Ferric oxalate solution will eventually go bad with time (faster with
heat or light.) The dry powder should last a very long time with proper
storage (no heat, no light, no moisture.) However each powder may have
a differing amount of inert contaminants influencing the final solution
strength.
Potassium oxalate developer will eventually go bad (fogging) with a lot
of use (many, many prints.)
The Pt and Pd double salts will not go bad unless contaminated, however
Na2PtCl4 (as well as other Pt salts with Na present) may go bad at
temperatures above 140F.
The use of cesium should not make the metal solution go bad.
It is important to NEVER use your Pt/Pd trays for silver work (negatives
or prints.) Have trays exclusively for Pt/Pd and mark them with a
permanent marker.
To my knowledge, no one has identified differences in prints due to the
spectrum of the lamps other than exposure times and perhaps contrast
(which could also be more likely due to the change in exposure.).
-- Jeffrey D. Mathias http://home.att.net/~jeffrey.d.mathias/
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