Digital BW, The Print

>I'm going to undertake the same task in the next days (I've just received
>the inks), with the following idea:

>1) Find out the actual density of the four FS inks (according to Paul Roark
>they should be very close to K = 100%, C = 84%, M = 38%, Y = 27%, which are
>the measured Piezo densities).

Those values are what I get on MY scanner.  I think the measured "densities"
are going to vary depending on your hardware.  The gamma settings are not
consistent among the scanners.  You need an actual Piezo test strip to use
as a standard.  You then measure that and use the reading you get with your
equipment to match the Piezo or other ink density.

So, eliminate the variables by using a standard test strip that is printed
and measured by the same equipment that will be used on the new inks.

>...
>I'm trying to develop an RGB/partitioned workflow for the MIS FS quad
>inkset.  I've tried Paul Roark's VM curves and "zeroing" the Blue
>curve that controls the toner and many other trial and error
>efforts.

You don't need to deal with the ink densities just to write partitioning
curves.  Just work from the 21-step test strip.  All it involves is a
feedback loop -- Print 21-step test file with curve X, measure 21-step test
strip densities, adjust curve X accordingly, save as curve X2, print test
strip with curve X2, ....

The MIS VM "warm" curve will give results that should look OK.  It holds the
lightest (yellow position, blue curve on the 1160) ink back the most.  It
then pulls it into play just enough to turn on the black jet.  Because the
yellow position FS ink is lighter than the toner the densities will be a bit
low, but they should be close.

Of course, the "warm" curve approach is not what you want with FS.  You want
the light ink to be used in the highlights.

My old PxoRGB4 curve should be close on an 1160 with a PC.  However, if I
were re-writing it today, I'd use the magenta position ink up in the
highlights more and reduce the slopes of the yellow-position ink (blue
curve).  That is, magenta is light enough to mix in with the yellow in the
highlights.  Keep cyan (red) out of the highlights.  Also, try to keep the
negative slopes to a minimum.  They cause a lot of the inconsistencies among
printer types.  The milder the curves, the more likely the curve will work
on other printer types.  That is one of the good points of the Woolf
workflow.  It may not be technically great, but it is fairly portable among
printers.

Paul
http://www.PaulRoark.com