From: Keith Gerling (kgerling@ameritech.net)
Date: 07/11/01-08:59:40 PM Z
Judy says,
Meanwhile, sorry to say, but in my experience, the "wealth of information"
on website below (which I haven't visited)-- if it's the one includes
lists of "staining" pigments & other official info on watercolors --
simply DOES NOT APPLY TO PIGMENTS FOR GUM. For instance, the Daniel Smith
catalog lists "staining" for its watercolors, but whatever the criteria
are for that determination, they don't mean diddle for gum printing.
For example, pthalo blue gets rating for strongest staining (4), but it
has proven to be almost the best clearing pigment in gum printing, in all
brands I've tried.
>
> http://www.handprint.com/HP/WCL/water.html
>
> I think you'll find a wealth of information there.
I urge you to take another look at this site, if you can. While not
inclusive (it doesn't mention "helios" anywhere and Linel isn't included,
either) it still has considerable information regarding pigments used,
saturation, lightfastedness, etc. It's free and its convenient.
As for its relevance to gum printing, I tend to disagree. It has served me
well, both in the selection of some alternate colors, and in explaining why
I've had some "weird" experiences with others. 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.
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.
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| World Journal of Post-Factory Photography > "HOW-TO and WHY"
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