From: Christina Z. Anderson (zphoto@montana.net)
Date: 03/20/03-09:07:11 AM Z
<Judy asks> Is your QV a paint? If so which one?
Q. violet by Daniel Smith.
>
> Of the others you name I've not tried the orange, or the "permanent red"
> (what pigment is that? AFAIK that's a name, not a pigment), and the only
> one of them I've had stain is the lamp black.
>
Whoops, typo--it's permananent *orange*, pigment PO62.
>
> > <Chris said>...my plastic *teaspoons* were stained with
> > quinacridone violet! :)
>
> That still doesn't prove anything for paper -- plastic my react
> differently... again, however, you don't say if that was a tube paint or
> pigment, and which brand.
>
Well it sure does to me, insofar as none of the other colors stained my
teaspoons, even lamp black. Even with a couple dishwashings it is purple.
But that does not mean I will can it for gum printing, as I happen to like
it. I just will use WAY less.
>
> I doubt acidity of gum is a factor in staining... unless you mean less
> acid more staining, because the Pictorialists often recommended letting
> the gum sour... I myself found no correlation of any factors with
> "acidity" of gum, although admittedly my acid-ometer was subnormal.
>
Wouldn't sour gum be more acid?
Alkalinity in the form of ammonia held back exposure. Acidity in the form
of lemon juice increased the sensitivity of the emulsion. No, I meant that
the more acid the gum was the faster the exposure would be timewise, so that
you would not get clearing of the highlights--overexposure, which you will
now point out :), is not staining in truth but provides for unclear whites.
>
> ><Chris said>In regards to below, Judy, I think it may be backwards from
what you
> > say. Most of the staining colors are the new synthetic
organics--thalos,
> > quinacridones, vat pigments, dioxazines, pyrroles. They are small
> > particled. The quinacridones are favored by the auto industry because
they
> > have small particle sizes. Not developed commercially until 1958 (p. 80
> > Page).
>
> <Judy said> Nope -- not backwards around here... It's not clear to me
whether you
> found this from testing or are quoting Hilary Page, who (as I noted) is
> writing about watercolor process not gum printing. Are you saying that you
> got staining with quinacridone red? With thalo blue? What brand? I often
> use both so strong they're too strong -- and no staining. They are the
> LEAST staining colors -- in NYC.
No, what you were backwards on is the particle size (see below) and the term
staining colors, as per below. Staining colors are smaller particled and
synthetic. But whether the color actually stains in gum printing is
different, of course as you say or we practice, since we combine it with gum
arabic. The only thing I will do in practice knowing which colors are
staining vs. non staining is make sure I have enough gum arabic to prevent
the staining from occurring and use less pigment anyway, which you can
certainly do because the colors are intense. The fact that a color is
smaller particle sized and would stain fits in with what you said a while
back on the list that some brands of tube paints are too finely ground and
stain.
Also, I find that bringing in other authorities from other disciplines
such as Page (who obviously spends her life researching paints) whether she
gum prints or not (presumably not) may enrich our understanding of what we
do, a sort of thinking outside the box.
Furthermore, Kosar's use of mild disclaimers is no different than
others on this list (including you and me) in essence saying YRMV--your
results may vary. (As an aside, one of the teachers I work with the
students call him a "walking disclaimer".)
<Judy says>But the explanation from the W-N lady of those
> > categories in *watercolor painting* was as I recall that the stainers
are
> > colors made from the old mineral pigments. The particles are fairly
large
> > and irregular & roll around and get stuck in the paper fibers. The
> > non-staining are the new synthetic colors with much finer particles,
> > "almost like dye."
Also, to address another post, to clarify, I sensitized a piece of paper
with dichromate mixed with gum arabic and let that DRY. Then I applied
powdered PIGMENT to the surface, which should be done by BRUSH. I don't
find that that would be harmful anymore than handling a sheet of dry
dichromate paper in the first place. I hope you did not think I was
brushing on dry dichromate powder (?)
Chris
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