Reading Luis Nadeau's book on the History of Carbon Printing, I came across the best pigments for 3 color carbon.
His first recommendation is from Ciba-Geigy:
65% Chromophtal Yellow 3G (CI pigment yellow 93)
35% Chromophtal Yellow GR 65 (CI pigment yellow 95)
-- These are disazo condensation pigments
Chromophtal Magenta 5077 (G) (CI pigment red 222)
-- A non laked high molecular azo pigment
Irgalite Blue L GLD (CI pigment blue 15.3)
-- a copper phtalocyanine
Another set offered by DuPont, is:
Dalamar (17) - a mono azo yellow
Monastral Red - a quinacridone
Monastral Blue - a phtalocyanine
I haven't looked extensively into obtaining these pigments, but there do appear to be a number of companies that make them. The question is of course, what is the minimum quantity and will they even give you the time of day if you're not a large manufacturer?
Now, something very interesting and that is also easily available to everyone are these Liquitex Proessional Acrylic Inks
The Phtalo Blue Green Shade is made with phtalocyanine blue (PB 15:3) - a direct hit!
The Quinacridone Magenta is made with quinacridone magenta (PR 122) - suspiciously close to CI pigment 222
The Yellow Medium Azo is made with arylide yellow 5GX (PY 74 LF) - a monoazo pigment
So it would appear that these inks are excellent matches in terms of the pigments for 3-color reproduction, the only concern being how an acrylic based emulsion would act in carbon printing. Any thoughts on that?