RE: Black spots in Pt./Pd.

DEAR SANDY,
        My 3 cents...
        I have never found any problem with Lennox so I feel that is a low
probability. What I DID find is that I have to clean the necks of my Ferric
Oxalate dropper bottles and the inside of the dropper cap EVERY TIME before
use. The crust of desiccated FO on them can fall into the solution as fine
clumps or crystals and create black spots upon development. I had black
spots on my prints using Lennox, Cranes Platinotype, and COT before I
started doing this and I have never had any spots since!
        If you don't use droppers look for some place where the FO can dry and
crystallize as the source of trouble.
        Some suggest that, if your metal solutions aren't warm enough you can get
precipitates that can cause similar problems but, living in the tropics, I
don't have that problem Some suggest that roller paper trimmers emit shards
of iron or steel that can cause the same spots but I use a roller trimmer
and have never had a problem with any of the papers above.

 Please check my website: http://www.bobkiss.com/

-----Original Message-----
From: Sandy King [mailto:sanking@clemson.edu]
Sent: Tuesday, August 09, 2005 11:57 AM
To: alt-photo-process-l@sask.usask.ca
Subject: Black spots in Pt./Pd.

Another Pt./Pd.question.

I have not done any Pt./Pd.printing in about 6-8 months and when I
began trying to calibrate my materials again I ran into a problem
that I have not seen before, small black spots on the print that
appear during development.

The chemistry that I am using 1 part of 25% ferric oxalate plus 1
part of 20% palladium chloride. The solutions are clear and are
giving very good Dmax, even though they were mixed several months ago.

The paper is Lenox, which I have not previously used for Pt./Pd. printing

Does this sound like a paper issue, chemistry issue, or some type of
contamination I am not understanding.

Sandy
Received on Tue Aug 9 10:23:24 2005