Digital BW, The Print

>I've got a second 1280 that I'm going to use exclusively for b&w. 
> ... thinking about making my own. 
>I very rarely tone b&w prints and when I do, I get 
>very good results using my colour printer 
>so am looking at a set of just black/grey inks.

Remember that the straight carbon inks are quite warm, about half way to
sepia.  So, a monotone neutral ink is, in fact, a toned ink.

The whole "variable tone" approach came only after I found that getting a
neutral tone on differing papers required different amounts of toning.  As
such, it was easier to have the toner be separate from the carbon inks and
use software (curves or other profiling method) to achieve the tone I was
after.

If you do want any toning, you'll find the inks often need more cyan or less
magenta (or R800 blue recommended if using MIS inks) in the shadows.  For
the midtones and lighter, a ratio of 2 R800 blue to 1 cyan is about right
for a slight positive Lab A in the final mix.  This too will vary, however,
which is why I went dual toners (3D or 4K+cm approaches).

If you want a pre-mixed monotone neutral set, the UT-R2 will almost
certainly work on the 1280.  A warm (carbon) ink in the yellow spot gets
some variability with the EZ-W being an option that may work better than the
R2-light warm ink.

>In addition to the Eboni Black, I'm considering 10%,
> 25%, 40%, 55% and 70% black formulations.

In the 4K+cm approach, I go from Eboni to K4 PK, which is probably close to
your 70% target. 

I would not recommend trying to dilute Eboni.  Start with MIS PK.  I have
diluted Eboni and it loses its relatively neutral tone.

To dilute down, if you want to use glossy paper, don't use the clear base
MIS sells.  Their Glop appears to be the same as the clear (slightly yellow)
base that is used for diluting the latest inks.

The standard dilutions are about a 1:3 ratio.  That is, LK is about .3 MP
PK; LLK is about .3 LK.  Using these standardized inks is useful.  (Note
that the K4 PK is a lower load than the older MIS 7600 or MP PK -- which are
now the same inksets.)  In the inks like UT2 and R2, the light inks are .3
of the dark inks.  The light carbon in the MIS inks is about .5 LK. (The
markings on the bottles MIS sells or used to sell, like "25%" etc., were
never actual dilution ratios.  They are just relative markings to let people
know which ink is more dilute.)

 
> And I typically do duo or tri toning ...

The 4K+cm could do that and would work on the 1280.  See
http://home1.gte.net/res09aij/4K+.pdf 

Have fun with the project.

Paul
www.PaulRoark.com