Digital BW, The Print

> ... that thing about the yellow channel being "re-engineered" 
>for greater saturation and a more useful gamut in the reds is 
>also something I heard when Ultrachome was first introduced. 
>Now whether that yellow has "dye" in it I don't know, and we
> may not even be able to know without some chemist breaking it down...

Yellow dye definitely has its uses.

My old FSN was the first B&W ink I know of that had almost no warm shift (on
EEM).  Yellow dye was a critical component of that mix.  I used the
different relative fade rates of yellow dye and cyan pigment to handle the
underlying poor delta e (color shifting) of the inks of the time.  I
intentionally matched the yellow fade rate with the warming rate, but, of
course, going in opposite directions.  So they cancelled each other out.  I
used rock-solid cyan to offset the yellow dye's visual impact on the inkset.
This cyan was so tough even back then that it improved the lightfastness of
the overall inkset, even with the yellow fading away. 

The general lesson is that to hold down delta e, dyes -- particularly yellow
-- can have a useful roll.  

The nice thing about yellow dye is that while it is high in gamut, it is low
in visual density.  So, while it fades, its impact on color is more
significant than its impact on density.  The bottom line was that my
original FSN had a much lower delta e than the existing quads of the time,
yet it also faded less.  That's not a bad combination.

With the advent of the higher-load and more lightfast carbon inks used in
the UT inks, I agonized over whether to also build in a counter-shift to
hold down the delta e. I opted not to, in part, as a matter of principle.  I
wanted to be able to print as pure a carbon image as possible.  The carbon
does warm shift a bit, and I could control that with yellow dye.  But, in
the case of the UT family, the pure-carbon & pure pigment goals won.  The
warm shifting of the carbon is so much less than the older inks' warm
shifting, that it just is not a big enough deal to resort to adding dyes.

Epson, might have made some different decisions in this regard. 

Epson's UC MSDS's suggest that those pigments are only partially carbon.

A UC-based quad inkset I made had the lowest delta e I've measured, but it
also had a slightly higher initial fade rate.  Maybe these are all
connected, but I'm speculating.




Paul
www.PaulRoark.com 
 










 methodically. Bottom
> line is it
> doesn't really matter except for semantic reasons. I was going to put on
> my website that I
> only work with pigments, no dyes, but I didn't say that ...... whatever.
> 
> I use both of these inksets and whatever they did to create UC works. Only
> if they made
> them for the 10K I already have. That printer is a much nicer machine all
> around, strong as
> an ox and significantly faster. I guess I'll have to go back to Lyson now
> for help.
> 
> That was great Paul, I'm printing it out for reference too.
> 
> John
> 
> 
> 
> 
> 
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