Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Peter Nelson" 
<pnweb@s...> wrote:

> If they're using standard pyrolytic carbon black (c2H(x) + Cr(x))
> then why/how does it yellow at all?   Are they really using iron 
> black or something else?    Or is it really the hehicle that's 
> yellowing?  (oil paints yellow over time not because of the 
pigment but because of the polymerization of the linseed oil.)

"hehicle"?  Make that 'vehicle'.