Digital BW, The Print

> I'm testing a sepia ink mix made from MIS M, Y, and Eboni black.  ...

Beware mixing different ink families.  They can be incompatible.  Eboni is
particularly sensitive and will precipitate unpredictably in all of the
available bases I've tried.  (Epson matte black is about the same.)

It's safest to, for example, to stay with a family of inks that are
engineered to be together.  I've been using the MIS 7600 family for the inks
I've been mixing lately.  Sadly, this family does not include Eboni.  The
only reason we can use it is because it is in a separate jet.  The MIS Photo
K, however, is in the 7600 family.  The older inks -- MIS VM, FS, original
Archival (not GP) do well with the older MIS base.  The 7600 family,
unfortunately, uses a special base that MIS might not sell.

What I've done with the UT2 inkset is designate the Yellow position as not
only the sepia toner position, but also a position that is available for
custom mixes.  Then the Sepia curves will probably print the custom mix.
Yet, the inkset will still be able to print the usual neutral through carbon
tones with the existing curves.  (They put so little of the yellow position
ink in the mix that the custom mix will probably not affect the image
significantly.  If it does, I can probably limit the yellow even more.)

For inputs in custom ink mixing for the yellow position of the UT2 inkset,
the whole MIS 7600 family of inks is readily available, but without the
clear base.  The current mix is 84% UT2 light magenta.  With 8% Y and 8% M,
this sepia tone can be printed with no additional inks all to and slightly
beyond 50%.  After that the carbon (magenta position) inks have to come in
to add more density.  However, especially if the mix is warm, the tone will
be controlled mostly by the custom mix.  IF the tone is cold, substitute the
cyan or a mix of cyan and magenta (which can be made to be neutral) to add
the required density.

If your custom mix is going to have stronger tones, to keep the density of
the yellow position ink about the same as it is now, the UT hex yellow
position ink can be used as a lighter gray base. 

You can get the densities very close to what you need by using Q-tip swabs
on EEM.  Just visual matching is enough to make the inksets work.  Don't
stick the Q-tip in completely in the ink, but rather let it touch the
surface and soak up the test ink.  Pull it out of the ink just before the
Q-tip is fully soaked.

For test mixing, Try counting drops into a bottle cap.  I use a big flat
screw-driver to dip out one drop at a time.  Let the drop slowly form and
fall into the cap.  This drop counting will get you amazingly close to
workable percentages.

The resulting inkset will, of course, continue to be RC compatible also.

At any rate, one of my goals with the UT2 inkset is to facilitate custom
mixing.  I'm sure that are lots more old darkroom hackers out there like me
who will never be satisfied just buying someone else's mix.

Have fun.

Paul
www.PaulRoark.com