pigments for gum bichromate

Dan Shapiro (dan@good.stanford.edu)
Mon, 12 Jun 95 15:50:54 -0700

Has anyone out there experimented with making their own pigments for
gum-printing (or painting)? The book "Colours of the Earth" (the rest
of the reference escapes me) describes the "old" technique (relative to
buying it in a tube) ... go for a drive and stop whenever you discover
an interestingly colored patch of earth (or rock). Take a sample home,
sift it, grind it with a dab of water, then proceed through several
sedimentation steps to collect the fine particles.

I tried the poor-man's approximation in some gum prints. Ground brick
makes a passable red, while ground up "orpiment" - a rather cheap rock
from rock-shops - makes a nice yellow.

Quality control is clearly an issue, but it is fun.

Dan Shapiro