unexpected pigments for gumprinting

Dan Shapiro (dan@lis.stanford.edu)
Fri, 13 May 94 11:22:19 -0700

As part of a project to develop an alternate gum dichromate
process, I am looking for commonly available, but unexpected
sources of pigments... things available from rocks, plants,
fireplaces, etc., just not out of a tube. Does anyone
have ideas about what might work?

My experiments to date suggest that it has to be finely powdered,
non absorbent, densely colored, and capable of going into
suspension with the colloid (e.g. gum arabic) - whatever
that entails. Sam Wang (from this list) suggested that
the ingredients *in* watercolors might be a good place to
start. Anyone know what they are, and if they are available
in the sense I describe?

Dan Shapiro
(dan@lis.stanford.edu)