Having to date made exactly two (2) tri-color gums, I comment rather
tentatively. But print #2 was cyan/magenta/yellow and tho it wasn't
perfect, the yellow wasn't a problem &, considering that I hadn't made a
test of any kind, I was thrilled.
The yellow was Rowney Permanent Yellow. The brochure from Rowney does not
state the pigment (grrrrr!), but lists it as "transparent." It also lists
Aureolin, Lemon Yellow and Indian Yellow as transparent, tho, in my
ignorance perhaps, I didn't see anything wrong with the Permanent Yellow.
But didn't someone mention Hansa yellow as a good process yellow? And
there's a new synthetic one, a D-word as I recall.
However, I wonder if having used a digital negative made a difference.
Theoretically, the spots of yellow might not be entirely in the same place
as the dots of red & blue -- or at least not all the same places --
whereas in continuous tone the tone areas would be much more contiguous --
maybe. Then again, Carson, your disaster gravure would have been in dots,
too, wouldn't it?
(Your story reminds me of the first class demo I gave about my 2nd year of
teaching -- enlarging onto lith film. Presto: the sheet emerged perfectly
clear. Technician had switched the developer & hypo.)
In any event I used .4 g yellow, 40 drops heavy gum, 20 drops water, 40
drops 26% am di. Maybe next time I would begin with .5 g pigment.
Judy