Digital BW, The Print

This is very interesting.  I've been trying to create a digital
printing method that I used to do in the darkroom.  It wasn't really
split toning but achieved a split tonality.  I would take a
traditional BW print that had been purposefully printed dark and
bleach it back heavily with a potassium ferrocyanide solution.  The
solution would not only bleach the highlights, but stain the upper
tonalities to a yellow/sepia hue.  Unfortunately, the technique was
quite difficult to control and even though I got several prints that I
liked it was a hit or miss affair.  

I've been able to duplicate the look to a great degree on the screen
using PhotoShop's duotone function with custom curves but I have yet
to get them to print.  Here are some examples:
http://homepage.mac.com/mojojones/display/page1.html  If you look at
the detail and duotone dialog you'll notice that the tonality stays
neutral and progressive until about 50% where it becomes light then
shifts to the yellow tone for the upper tones prematurely bleeding off
to white (the bleached effect).

I first tried to print these images with standard color inks but the
neutral tones where not neutral.  So after reading about MIS viable
tone inks I thought maybe I could to it in a similar way.  So I set up
an old 3000 with the FSN inkset and replaced the Magenta place with a
custom mixed yellow/sepia tint the was a similar density to the K tint
it replaced.  I've only just started experimenting but as yet the
results haven't been to acceptable.  I'm not getting enough density in
the yellow/sepia tones and they are going green due to the blue tint.
 I'll probably have to add some black to increase the density of the
custom tint and restrict the blue tint to the lower tones.

John J.