Re: gum bichromate

Judy Seigel (jseigel@panix.com)
Sun, 11 Jun 1995 02:21:54 -0400 (EDT)

On Sat, 10 Jun 1995, Peter Marshall wrote:
> > Here in the UK I would recommend the use of 'Gloy Gum' which is made by
> Henkel in England and is a PVA gum of some kind. It keeps very well, is a

It sounds like something to try. I'll ask a friend to bring me some.

> artists' suppliers. >
> From whom you can also buy solid pigments for gum use - this saves any
> problems in buying tubes of colour where the formulation may change or
> age. A jar of pigment will last for ever - unless you go into mass

When you say "solid pigments" is that what we mean by "powdered" or "dry"
pigments? I have used them for gum, in fact have a carton full,
but I find they're not finely enough ground. The attempt to grind them
finer is tedious and who needs more dry chemicals floating in air? I also
bought pigments in moist form from a fellow in the east village, but they
didn't clear at all. He (Guerra) said it was probably the dispersal
agent. The preference for finely ground, incidentally, is because you can
only get as many values as there are pigment particles in an emulsion
layer. If the particles are bigger, there aren't as many of them.

BTW, and for what it's worth, I tested every brand of water color sold here
in one color (burnt sienna). The richest color and best clearing was
Rowney (also English I believe and about half the price of Winsor Newton).
Of course maybe some other brand is better in a different color, but
I live dangerously.

Also BTW, there used to be a set of cheap Japanese
tube watercolors, "Niji" brand, that cost $4 for about 8 tiny tubes, and
cleared wonderfully; students relied on it. Now that brand has become
"Rainbow" and harder to find. Most other cheap sets of
Japanese watercolors do NOT work for gum.

Judy