On Wed, 1 Jun 2005, Christina Z. Anderson wrote:
>
>
>> (CZA) to test the old adage that chrome colors affect the
>>> process adversely, but to no avail.
>> (KT) I've used viridian and chromium oxide green, both chromium paints,
>> with
>> no problem. I'm convinced that's just another myth.
>
> (CZA) That would be my guess, too. BUT, it was repeated often enough in the
> lit to test it. Demachy--it either caused spontaneous insolubilization or
> didn't allow the coat to harden, Kosar said insolubilization, then Crawford,
> Frederick, Reeve, Scopick, Blacklow, Hirsch.....that is just with a quick
> once-thru on my notes. I'm not saying that repeating it makes it true, of
> course :)
My guess would be they copied from each other just like (OK close your
eyes) the infamous Gum-Pigment-Ratio test. Or the Cyano toner in
Crawford. Among many such shibboleths. It's possible also that the ur
chrome pigment was something else, or had more chrome, or the originator
had done something else to it that day... (Aesops fables is right.)
> ...Judy said ultramarine gave her/her students
> trouble. I, and a couple others, find when I use ultramarine it gives off a
> sulfur smell. Yukky and unpleasant, but it still works. I have not found a
> pigment that doesn't work, just some I don't prefer--dioxazine purple being
> one that I could not use if I didn't size paper because it stained royally.
Modern ultramarine is a manufactured color... so who can say the process,
let alone the raw materials, is the same each time. I had a tube of WN
ultramarine when I began serious testing of gum variables -- maybe 10 or
so years ago. The paint in THAT tube didn't clear in many combinations. It
stained the paper whites. It may have been the water, that particular
tube, those materials, air pollution, whatever. But I liked thalo better
for many purposes... its greater covering power meant you needed less,
which permitted more control over other variables (like ratio of gum &
sensitizer strength).
Rowney ultramarine, BTW, was fine.
J.
Received on Wed Jun 1 17:01:11 2005
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