Digital BW, The Print

Peter,

I'm not sure exactly what form of carbon is in the inks we use.  The Epson
MSDSs tend to list carbon as, at most, just one of the ingredients.  I have
not seen MSDSs for the MIS inks.   I suspect no one out there wants us to
know exactly what is in these inks.

So, I'm using "carbon" loosely.  I have assumed the carbon is mostly
graphite, but I don't know.

I doubt very much that the black inks contain black iron oxide.  Its
specific gravity is way too high.

My tests, however, are consistent with what I've heard -- that carbon does
yellow slightly.  I can't tell why or, for example, whether it is the base
or the pigment itself.  

Paul
www.PaulRoark.com 
_________________________

-----Original Message-----
From: Peter Nelson [mailto:pnweb@...] 
Sent: Monday, May 03, 2004 8:33 AM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: [Digital BW] Re: 1270 B&W (was Clayton's Site)

--- 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.)