Also, in your suggestion above, what does the chrome alum do? Is the
purpose
of adding the alum mainly to harden the gelatine?
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Hello Dave
Oil pigment printing was what the secessionists went on to when they got
bored with gum. It had the advantage that they could use the same contact
negatives.
You coat water-colour paper with a 5% and then two 7 % coats of gelatine.
When it is dry you dichromate it as you do with carbon, and then expose it
under the negative and the wash away the dichromate, at which stage you
have a matrix, similar to that after bleaching and fixing a bromoil, which
you then soak in water.
You then ink it up in the same way with greasy inks that take to the
exposed gelatine, but not the unexposed which is swollen with the water..
As a water-colourist I suspect that you might find this processs more
satisfying.
You can then make transfer prints using your inked print as a lithographic
plate.
My two separate workshops all day on Saturdays and Tuesdays next term cover
gum, bromoil and pigment printing.
My comment on the alum was meant as a question to others on the list. I
wondered what they used . The alum must be in a small enough quantity to
harden the gelatine suffficiently to keep it adhered to the paper but not
enough to stop it swelling. I do not add alum to the 7% coats.
Terry King