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Daniel Barber complains:
>i hope someone can help me. i print palladium on platinotype, and ive been
>getting these horribly annoying tiny red dots on the paper about five
>minutes into the final bath. one second the paper is clean, the next second
>this little red dot has appeared, and as far as i can tell there is no way
>to get it off.
Most likely it is iron or steel particles. They could have originally been
real teensy weensy so you could not see them. The primary culprit we have
traced down is self sharpening paper cutters.
I once had a customer named Marc Biggins back when we were in LA who
suddenly had a plague of spots. He had a commercial project that had to go
out and he was near suicidal. (I am sure there are those here who know the
feeling!) I felt that I was near death from the flu, but he pleaded and I
went over to his studio to try to debug the situation. (I came under the
agreement that if I solved it, there was to be dinner at the restaurant of
my choice!) I watched Marc make a print. The first thing he did was to pull
out a large sheet of paper put it up on the table and use a steel rule and
razor knife to cut the paper. "Whoa!", I said. (Sort of like a soap opera
isn't it?) We stopped everything and started over. I took out a sheet of
paper from the bottom of the stack, tore it into a smaller piece and then
took the razor knife and steel rule and holding both above the paper,
dragged the razor knife along the edge of the rule. We could see nothing on
the paper, thus the scientific conclusion of "teensy weensy". We then coated
it and gave it a short exposure without a negative to form just a light gray
image. We developed it, and voila, hundreds of black specks all over the
print. He and his wife, and Melody and I, had a nice dinner at La Boheme
by the way.
Platinum and palladium will reduce out (plate out) in the presence of iron
compounds. For instance we once had a workshop teacher who put 100 gms of
potassium chloroplatinite in the approprate amount of water into a stainless
steel coffee pot to dissolve it. He called me when all he could detect was a
slightly pink liquid in the pot. What he had done was to plate his coffee
pot with platinum.
I am not sure of what causes the "red" component in Daniel's missive. We
have had some reports of red dot contamination that appear to be from
iron/steel though most of the time they are black. If Daniel can snip out a
couple of these dots and send them to the address below, I'll take a peek at
them with this big sexy microscope I was just loaned from one of the List
members. Once we solve the problem, these pieces can become part of our new
rogues gallery of problems.
Sorry to ramble on, just thought this info may be of some use.
Bostick & Sullivan
1541 Center Dr.
Santa Fe, New Mexico
87505