Digital BW, The Print

>
> I would guess that UltraChrome inks are pure pigment, with no liquid dyes in
> the fluid.  (A more interesting question is whether the acrylic coatings
> have dyes impregnated in them, and I have no clue on this.)
> 
> Anyway, that is my long-winded, best guess as to the pigments that are in
> both the Epson and third-party products.  There are many minor variations of
> these basic pigment classes that alter the exact chemical structures and
> colors.
> 
> Paul
> www.PaulRoark.com

Beatiful synopsis Paul...

I've read a bit about colour chemistry and I agree on most points. I did read 
somewhere on the net though, that the biggest difference between Epson's Archival 
inkset and the UltraChrome is that to improve the colour gamut they opted to add 
some dye to the yellow ink to improve colour space at the expense of longevity.
Yellow is the most ephemeral of all inks, even in lithography. If you put a litho in 
strong sunlight the yellow will go fast and then the magenta and lastly that stable 
Phthalocyanine you spoke of.
I've saved what you wrote as a nice summary for when I get asked these questions. 
You aren't long winded but I am!

Brian