Digital BW, The Print

Eric,

>... regarding the solarization ... using MIS Ultrachrome on Glossy ...

I assume you are using the MIS Ultra Tone B&W inkset, not the Epson color
UltraChrome inkset or the MIS clone of it.

>using Epson 1270

There are older curves that are for the PC and another set for the Mac.
There is also a newer set for both that uses the No Color Adjustment
setting.  So, for either computer there are 2 full sets of curves for the
1270.  The first thing to do would be to try the curves and see if one set
is better than the other.

Both sets were written for Epson Enhanced/Archival Matte paper, however.  So
if the paper is the cause of the problem -- which is likely -- the results
may not be much different.

>I believe you suggested I work on adjusting the curves. I am curious
>what is the cause of the solarization and where I might start in
>approaching adjustments of the curves.

I'm not 100% sure what you mean by "solarization."  It might be a flat spot
in the grayscale curve, or some might see the "bronzing" and describe it as
this effect.  Both are defects that may be problematic with RC papers.  The
bronzing seems to be something that sprays might fix, and some papers have
very little.

As to the grayscale ramp flat spots, most papers absorb the inks slightly
differently.  Most matte papers are close enough that the "canned" curves
work OK with a number of different matte papers.  The RC/glossy papers, are,
no doubt, more divergent from the matte papers in their characteristics.  I
was surprised the existing curves worked as well as they did on the RC
papers I tested.  The warm curves were the only ones I saw serious flat
spots on.

One thing that appears to explain some of the problems is that the RC papers
may not be able to handle as much ink as the matte papers.  One 1160 Ultra
Tone (UT) user found that the new curves I wrote for the 1160 curved the
problems he was having.  The difference in the curves that might account for
the improvement is that I pulled the light gray curve back up after the dark
gray (cyan) started to take over the image-forming work.  This probably
reduced the total amount of ink on the paper.

So, one thing I would consider in re-writing the 1270 (or any) curves is to
pull that light ink out of there as soon as possible.  Rely on the cyan ink
for the midtone and all but deep shadows.

By pulling the light gray back up you can also hold the black ink back until
the very deepest shadows.  With the Eboni ink, I've found this really
improves shadow smoothness.  I have not done enough work with RC paper to
know the effect on them.  Frankly, I'm not sure there is an RC paper I'm
interested in enough to write curves for at this point.  If there is a
clearly superior one, I'll buy some and see what works with it.

I hope this gives you some help in fighting the problem.

Paul
http://www.PaulRoark.com