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Re: Dichromate stains--another clue?
On further thought it occurs to me that this tanning effect may be the
answer to the puzzle about why my friend insists that ammonium
dichromate is useless for gum printing, when it works fine for me and
lots of other people. He uses a very intense (3000 watt if I remember
right) light source. Might it be that the strong light in combination
with the faster ammonium dichromate could increase the probability of
getting this green compound, even with fairly short exposures, depending
on what his negatives are like? It seems a logical possibility to me.
Katharine Thayer
P.S. I want to improve a sentence in my last post for clarification. I
said that the yellow dichromate stain can be seen in the back of the
paper. I wish I'd said that the stain can *best* be seen by looking at
the back of the paper; if you look for it in the print itself you could
miss it, but it will be evident on looking at the back. On the other
hand, the green "tanning" effect is seen in the gum, in the print
itself.