Digital BW, The Print

Carl,

> ... I'm not happy with the MIS
> UT7 LK that I've been using in my 4000 because I've been getting hue
> shifts (towards yellow) when printing for neutral and I have to add
> LM and LC to get neutrality.  The whole point of switching to the UT7
> LK was to avoid toning with the cyan and magenta inks, but It doesn't
> work.

The UT7 LK(N) was mixed only to give more neutral shadows when the 2200
Epson driver was used in slider mode.  It is not an appropriate mix for a
mid-tone neutral ink.

> Using a 50:50 mix of UT7 LC and LM position grays gets me a
> more neutral composite gray in my 2200 

That is exactly as it should be.  These inks are equal in density to about a
50% dilution of LK.  I would expect the Epson lightest ink to be at least a
30% dilution of LK.  That is about the dilution from PK to LK in MIS inks.

I'm starting to use FS-Y (the same density as the old PiezoBW lightest --
Y-position -- ink) in my UT7 setup to get the smoothest highlights possible.
But, its dilution is closer to the equivalent of only 8% LK.  The
density-pigment load (dilution) curve is very non-linear near the ends.

>  I would also like to have a MATCHED, NEUTRAL K and LK  ...

The problem is that the same ratio of MIS R800 Blue to 7600 Cyan ("RB:C"
ratio) changes as one moves up the scale.  If one uses a static mix like the
UT1 toner, which was made for quad printers, what looks best at the 50%
patch will look very magenta in the shadows of many papers.  Counteracting
this magenta bias of the shadows is why the LKN was mixed the way it was.

For those using LK as the neutral and highlight ink, the color ink mix (RB:C
ratio) should be like the UT1 toner.  That is what the UT2 and UT7 cold
light gray inks use.  The darker cold grays, however, have a different color
mix.  

(Carl, if you wanted to try an educated "shot-in-the-dark" LKN-2 mix with
the standard midtone color mix, I could send you a bottle.  However, I don't
have the time right now to do the testing needed to get the gamut such that
it would match PKN right on.  Then again, it would be different for
different papers anyway.  That's a major reason why I prefer a variable-tone
approach.)

My next ink project is to focus on control of the shadows for my upgraded
7600 UT7, since that can now be done with a rip.  That is, I'll add control
of the green-magenta axis in the shadows, as well as the current carbon
(yellow)-blue axis.  This project is going to have to wait until late
August, however.

Paul
www.PaulRoark.com