Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Paul Roark" 
<paul.roark@v...> wrote:
> Stuart,

> >2.Is there any advantage to the UT1 or 2 on the 1270 ?
> 
> The UT inks are more lightfast and don't warm nearly as much.  
(Carbon
> yellows a bit.)  

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.)