From: Judy Seigel (jseigel@panix.com)
Date: 07/13/01-01:39:04 AM Z
On Wed, 11 Jul 2001, Keith Gerling wrote:
> ... As far as the stain rating
> goes, you will note that ALL of the pthalo blues get either a 3 or a 4
> rating. Most of the "3"'s I've never used (or even have heard of), but
> Rowney gets a "3", and, at least for me, Rowney is less staining than Smith.
Is there a definition for *staining*? I suspect it refers to the ability
of watercolor pigments to be lifted off the paper, which is a thing people
do who paint with watercolors, not the ability to withstand bleach. For
instance, I have a bottle of something from Winsor Newton called "Lifting
Preparation," or "corrective medium."
The label says, "Apply directly to paper and allow to dry before painting.
The preparation then allows dry washes, including staining colours, to be
more easily lifted from paper with a wet brush, ideal for making
corrections."
This solution had ZERO effect in gum printing, at least in the limited
tests I did. As noted, whatever the mechanism of the so-called staining
colors is, in my experience it is NOT correlated with staining in gum
printing. But in any event, BLEACHING is something else entirely.
Yes, the bleach idea may have come from Post-Factory #2 -- an article
titled "How to Cheat at Gum." I wrote about using it to clean up borders,
or get other spots, grunge etc., out, saying finally, "This is the time
when you don't appreciate 'light-fast' colors." In any event, the bleach
does usually melt the underlying gelatin size and clear pigment that way.
If the paint has worked its way through the size into the paper (which a
"staining" color might, I'd guess, if gum worked that way, which I
continue to doubt !!!), it will still bleach IF the pigment bleaches -- or
so I have found & surmised. If your blue didn't bleach out, I'd figure
it's simply more bleach-resistant.... which ought to (perhaps) mean more
archival. I did find colors that would not bleach, or not readily, but I
haven't done it lately & don't remember which ones.
> Speaking of blue, and of staining, occasionally (like 90% of the time!) I
> have unsuccessful prints and have attempted to use a strong Clorox solution
> to bring the paper back to square one for re-use (a tip from Post-Factory?).
> For the most part, it works: the black, yellow, and magenta pigments slough
> off. But there is almost always a blue remnant, meaning that the paper has
> to be used in registration for the same image. While the initial
> development of the Dan Smith pthalo does wash out of the highlights, the
> bleaching does not get rid of the blue in dark areas. I'm not sure if this
> is an example of "staining" but it certainly doesn't happen with any other
> color.
Again, that sounds to me not like an example of staining, but of not
bleaching. And for not bleaching I wonder about Quinacridone red... among
others.
If you're feeling experimentally inclined -- you might put some of those
pigments on, say, a piece of glass, and see what clorox does to them when
they can't have soaked into or "stained" anything !! ??
cheers,
Judy
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