Re: using powdered pigments in gum

I've been using Varn gum with powdered pigments for many years. In my
experience, it does not go bad or spoil. I've never added extra
preservative, because there's never been a need to. If you mix a stock
solution of pigment/gum, stir it up thoroughly before use, as the pigment
will settle in the bottom of the container. I usually prepare 200 ml
bottles with stock solutions, e.g. 1g Winsor Newton Winsor Blue/130 ml Varn
gum.

Best regards,
Dave in Wyoming

>
> 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 17:37:25 2004