From: Judy Seigel (jseigel@panix.com)
Date: 03/27/01-01:13:18 AM Z
On Tue, 27 Mar 2001, Eric Neilsen wrote:
> Dave, With platinum printing , one can mix platinum and palladium ( in all
> their various salts , sodium, ammonium, potassium) to affect color and
> contrast. Have you or can you mix ammonium dichromate and potassium
> dichromate to adjust speed and contrast with gum?
You can mix about anything you want into a gum emulsion (sugar, epsom
salts, ginger ale), but I'd guess that mixing those two would introduce a
whole new set of variables (tho gum is so forgiving, it might be fun to
try) -- contrast is more rationally controlled by varying the strength of
the dichromate (which can be anywhere from 2% to saturation) and the
ratio of gum /dichromate.
My thought was to ask Amanda if anything else was changed at the same
time: new tube of paint, new batch of paper.... whatever. I've never seen
ANY color difference between am di & potass di, in a fair number of tests.
SOME COLORS or makes showed a greater tendency to dichromate stain under
the test conditions with the am di (tho not in actual prints), others
didn't. My impression is that by varying the above, either one can be made
to act a lot like the other... which is to say, there is no *best*
solution (in my experience), just the one you're used to.
Judy
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