Re: using powdered pigments in gum

Jack,
     I have never added preservative to commercially mixed gums, nor needed
to, even using 6 year old gum. Even my tube pigments that I mixed in that
gum 6 years ago as stock solutions were finely preserved.
     The first time I had gum go sour was when I mixed up my own batch of
gum from powder to mix with the powdered pigments, and did not preserve it.
That happened within a week.
     Now I preserve it with an added 1/2 teaspoon sodium benzoate dissolved
in hot water first and added to the cold water that I mix the gum up with,
for every 100g powdered gum. Why not just add your thymol or benzoate and
be on the safe side? The benzoate has not affected the performance of the
gum at all that I can tell, after a couple hundred prints.. I do find it
weird that this has never happened to you before and is now, with the Varn.
     As an aside, the only other problem I have noticed is bad smells of
throw up/poop (is that descriptive enough?) emanating from certain pigments
in combination with the gum, that is, when I mixed cadmium yellow with
nickel titanate, and sometimes when I use ultramarine blue. Furthermore, I
am convinced after having sized and used up all my old aquarelle paper now
(thank heavens) and put up with that wet dog smell enough that I will never
again--there was a point where I would coat that paper and I couldn't even
walk into the room without feeling like puking because of the smell--I am
convinced the paper had gone sour. Or bad. Some had brown spots, some
stains, they curled horribly, I will never use aquarelle again in my
practice. Or old aquarelle, anyway.
    One last thing, there are some paints that right out of the tube
stink--M Graham sepia, for one. It smells like sour gum arabic to me. Not
that this is your problem, in that you're using powder.
Chris
----- Original Message -----
From: "Jack Brubaker" <jack@jackbrubaker.com>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Tuesday, May 04, 2004 1:32 PM
Subject: 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 Wed May 5 01:45:49 2004