using powdered pigments in gum

Dear list,

I'm looking for advice. A couple months ago I made up several batches of
gum-pigment for gum printing. I used the same VARN gum I have been using for
the last year. The pigments are old stock I have had for 40 years but never
used for a large batch to use over an extended time before. I should mention
that the pigment was stored in a drafty shed for many years and the
cardboard canisters had failed allowing some organic material like leaf
fragments to fall into the powders. As a result I had to sift out some small
objects. Within a week the solutions I made went sour. Because I ground the
mix into such a thick, pigment-rich, consistency (more like tube color) I
can dilute it with the addition of more gum at printing time and it works
fine. But, now I want to make some new batches thin enough to use as a
straight printing mix. Would this spoilage be possible with fresh pigments?
Do those of you who make up gum-pigment solutions add any extra
preservative. I have some thymol that I used in a gum solution that I made
from dry gum. Should I put some of the thymol in the VARN gum next time? Any
other thought or suggestions would be appreciated.

Jack Brubaker
Received on Tue May 4 11:51:46 2004