It is hard to know exactly what you are looking for in violet black but you
might try a combination of Sumi Ink plus small quantities of blue and
magenta. After you have added the pigment to the gelatin solution you can
get a pretty good idea of the final color by spreading a drop very thinly
on a sheet of paper. If you don't like what you see at this point adjust
with more of one of the pigments.
Sandy King
>I'm also interested in using a pigment other than Sumi ink, which I tried in
>my initial carbon prints. I'm fortunate to have access to quite a supply of
>Winsor/Newton water colors, and would like to mix a pigment color that
>produces a cold black to violet black.
>
>If anyone has suggestions for other papers to try and/or pigment
>combinations, I would be grateful.
>
>Tom Hawkins