Digital BW, The Print

Daniel,

You wrote:

>I'm using the B&W Ultra Tone inkset with MIS 7600 Archival Pigment Light
>Black in the light black position (since there's no Ultra Tone ink for
>that) on an Epson Stylus Photo 2100.

> ...
>
> I'm having serious trouble getting the ultratones to work
> properly on glossy papers with my 2100. ...
> it seems to be the light black ink interfering, making it
> impossible to cool down the shadow areas to anything less
> than a really brownish gray. The problem is also there to a
> much lesser extent on matte papers, but the prints I get
> still appear totally neutral to my eyes at least, so there
> it's not a problem.
>
> Here's a scan of a 21+100 step wedge on both matte and glossy
> papers where I toned the image with an extreme amount of
> magenta, which in theory should make the entire curve blue,
> but you'll see that from about 85% the curve starts turning brown.
>
> http://daniel.staver.no/img/ultratones2100.jpg
>
> Any suggestions on what I could do to solve this problem? I
> don't think any kind of curve adjustment will solve this,


I agree that simple curves are not likely to cure your problem.

You may have noticed that once the 7600 was out I purchased a 7500.  I don't
think the 2100/2200/7600/9600 driver is going to lend itself to the standard
variable-tone inkset arrangement.

To control the tones in the shadows you need to be able to have the toner
full-on as far down in the shadows as possible.  Usually you're just
fighting the black ink, which is warm.  As the black is fed in, the color
inks are cut back to stop over-loading the paper.  Part of the original VM
toner design was to get the gamut of the toner to just enough to give a
neutral 90% patch with the 1160 workflow that I was using.

With the 2100 starting to feed the light (warm) black in earlier, this is
going to be a problem.  Also, the cyan tone of the standard variable-tone,
vm inksets is slightly darker than the light black.  This is might make
shadow contrast hard to maintain with some tones.  Bottom line -- the inkset
is probably going to have to be modified to work with the UltraChrome
drivers.


> I think the solution must be in changing the light black or
> one of the other inks somehow.

Yes, I agree.

> I've been wondering whether I
> could mix a more neutral light black ...

I think a more neutral light black would help.  There may still be density
anomalies, however.

To be frank, I'm not sure the 2100, et al., will really be that useful until
a good RIP is out that can control each cart individually.  If we get such a
product and it's reasonably priced, I might just go that route with the UC
printers.  On the other hand, I may just skip the 7-ink printer generation
entirely.  The 8-inkers may be out soon enough.


>What would be the best way to mix a neutral ink?

Try throwing cyan and magenta MIS 7600 color pigments into Photo K.  Expect
to put a little more magenta than cyan into the mix.  You can add one-drop
amounts (I use a flat screw-driver to get good, consistent drops) into a
bottle cap to mix small samples and then spread them on a piece of EEM with
to Q-tip.  When the tone looks right, just scale it up.  You can get fairly
close this way.  I'd take a wild guess that close to 20% color pigs might be
what you'd need.  These will make the Photo K lighter.  You may want to end
up with a mix that is darker than the cyan UT ink.  (All the crossovers in
that driver could continue to make things difficult.)

Good luck.  Let us know how it goes.

Paul
http://www.PaulRoark.com