pigments for gum and PDN

Good morning all!

The discussion came up about the value of worrying about pigments and
archivalness, etc. Personally I am now persuaded to always talk about a
pigment by brand AND number (I'll try to include proprietary name, too, if I
have it handy).

After the Maimeri PY139 Perm Yellow Deep vs. M. Graham discontinued PY110
issue, and because this last month I have been working out curves for gum, I
went ahead and mixed up all my colors (22) and test stripped/wedged my life
away. I finally concentrated on 8 yellows, 8 reds, and 2 blues. (BTW
Holbein OperaPR122/BV10 isn't any great shakes anyway in a gum coat).

It's amazing what you discover by this (test strips under controlled
circumstances).

I was so bummed, because the yellow I chose as my fave is fugitive...it is
Holbein Permanent Yellow Light PY53/PY55...or, at least, one of those is
fugitive (PY55). Talk about manufacturers mislabeling! Or did PY55
suddenly become permanent??

But I wanted to add a note about the PY110 M. Graham's old gamboge vs.
PY151/P062 M. Graham's new gamboge vs. Maimeri PY139 vs. the REAL gamboge
Winsor Newton NY24. The new Graham gamboge is much closer to true gamboge,
but isn't even CLOSE to their old gamboge. The color that comes closest of
all my yellows to imitating M. Graham's PY110 is the Maimeri PY139 Permanent
Yellow Deep, albeit a tad more opaque and in gum and with dichromate
exposure, a slight tad warmer than the PY110. But with D. Smith having
their own PY110, it is a moot point. However, I might consider the Maimeri
PY139 my golden yellow of choice, if needing a bit more covering power.

The most fascinating thing is finding that the colors each have their own
exposure times and own curve, but so far it seems within a family of colors
(yellow, for instance) the curve stays similar. Given differences in
pigment load and opacity within paints, I find this intriguing and requiring
more testing. I have not tested a cad yellow yet.

I also realize from doing the PDN process that in gum printing we are
talking about an entirely different thing than in other processes, gum
printing really not being photographic per se but photo sensitive. In other
words, you are building up a thickness of layers, therefore vertically if
you will. For instance, more exposure will produce a deeper color because
less of the color layer washes away, so on and so forth. And you also don't
have a one shot deal as in palladium or silver where you get it and that's
it, sort of. So I suppose no matter what is said about gum there's always a
"but".

Today I print a side by side gum my old way (one curve for all three layers,
black ink only neg on Photo Warehouse film)and then with all three layers
done with their own color and curves (PDN method, colorized negs with 3
separate curves and 3 separate printing times, no black ink, Pictorico
film), to see if there is a benefit with gum this way or not. I have no
clue. I am going to predict that gum is such a variable process that it
does not matter, being able to take care of these variables through
development and by eye, but I'd love to be proven wrong. I know with cyano,
silver, palladium and solarplate the PDN system works like a charm. I also
know that at the least I have learned lots more about how gum and color
respond by doing it.

More later,
Chris
Received on Fri Jun 10 10:35:19 2005