From: Katharine Thayer (kthayer@pacifier.com)
Date: 02/24/03-03:07:31 AM Z
I always write and send responses fast, and then often later think of
something else I wanted to say. So here's my P.S. for my last post:
About clearing agents: I said I have always used sodium bisulphite, but
to be accurate I should add that I almost never have a need to clear my
prints, and when I have it's usually not because of dichromate in the
print itself but because there was some dichromate splashed on the work
table that I didn't see, and it soaked into the back of the paper,
leaving a yellow spot.
But I also think that the paper and the sizing have a lot to do with
whether you get dichromate stains or not. When I was using Arches paper
I never had to clear except as reported above, but when I was testing
various paper/sizing combinations to replace the ARches, I found that
some paper/sixing combinations are extremely prone to retaining a yellow
stain from the dichromate that has to be cleared out of the paper; it
won't soak out in the water development.
Another thing about dichromate stains to be aware of: there are two
kinds of dichromate stains. There's the bright yellow stain of
unreduced dicrhomate, and the variously-colored green or brown stain of
the reduced chromium: chromium oxide and various intermediate products.
It's the chromium oxide that reportedly sometimes needs sulfuric acid to
clear.
kt
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