From: Judy Seigel (jseigel@panix.com)
Date: 07/10/01-01:06:03 AM Z
On Mon, 9 Jul 2001, George Huczek wrote:
> I am doing gum prints with Linel helios yellow 1:1 gum and pot. di.
> sensitizer.
>
> After exposure the pigment changes from a bright yellow to an olive green.
> After development, drying and clearing with potassium metabisulfite the
> olive green colour persists, so I don't suspect dichromate stain. The
> highlights cleared to the paper base colour. Can anyone suggest why the
> pigment colour changed after UV exposure?
George,
FWIW, I'm always suspicious of a paint with a name like helios.... Unless
the label ALSO tells you the actual pigment. I haven't tried the vaunted
Linel colors yet, tho I expect to -- but I'd be curious if you got that
green effect with, say, Daniel Smith Hansa yellow, which is a "process"
yellow... or Rowney Permanent Yellow, which is a hansa or arylide yellow,
or any of quite a few other yellows that are standard pigments. (They also
have "cadmium yellow" tho I don't think that has cadmium in it any more.)
Meanwhile, they can change "helios" at will, and you'll never know --
until maybe it turns green (which I've never seen happen -- yet).
Judy
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