Re: gum bichromate

Adam F. Kimball (afk@SIRIUS.COM)
Sat, 24 Jun 95 11:28:22 -0700

Alright... All of this discussion of gum printing has gotten into me. I
went out yesterday and bought some materials for the process, jumped into
the darkroom, and emerged a few hours later with some absolutely horrid
prints! :) Seriously harsh brushing and high-powered water couldn't break
through the pigment. It would flake, but it wouldn't clear at all. I
wondered about the exposure I gave the print, so I printed a step-wedge
for three minutes under my UV fluroscents- and the same effect. My materials:

Saturated solution of pot. dichromate
Liquid gum-arabic by Winsor & Newton (I know this stuff is extremely $$$ but
I had the bug to print RIGHT NOW and I couldn't find anything else.)
Winsor & Newton Lamp Black tube pigment
Fabriano Artistico watercolor paper

I figured I'd start out with Crawfords method so my solutions were combined

20ml Gum arabic
1g pigment
(thoroughly mixed with pestle)
20ml Pot Dichromate (25g:160ml distilled water)

I coated a number of sheets (all with different amounts of sensitizer) and
processed them all "automatically" in water around 75 degrees (room temp).
None of them even looked close to decent.