Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Clayton Jones" 
<cj@c...> wrote:
>...
> The blackest possible print area can only be achieved when there is
> 100% coverage by only the K ink.
>...

I haven't been able to find a general rule for whether or not it
is advantageous to add another ink to the black without adding a 
second black: it seems to depend on the inkset and the paper. Here, 
as an example, are some of my results from Sundance Septone inks in a 
2200, with IJC/OPM, and Clayton Jones' BO method with the Epson 
driver:

HPR: no increase over BO DMax by mixing dark grey with the black, no 
decrease either.

Entrada Fine Art: slight loss of DMax (0.01 to 0.03) by mixing 
neutral dark grey with the black, no change or slight increase with 
warm dark grey.

Merlin Photo: increase of about 0.1 in DMax by mixing neutral dark 
grey with the black – I have the feeling that the paper can
handle a lot of ink.

Ilford Galerie Smooth Glossy; Kokopelli Photo Gloss: the results seem 
to depend on the nature of the subsequent coating, so the number of 
variations is large - black ink amount, overlay ink colour(s) and 
amount(s), coating - and I haven't drawn clear conclusions yet. I 
have the impression that some coatings (eg rolled-on water-based 
varnish) achieve significant increases in DMax (typically 0.6 to 0.7 
to give a final DMax of around 2.6) by allowing some unabsorbed ink 
to migrate a very short distance upwards into the coating, creating 
an extremely thin layer of black varnish. If I begin by misting the 
surface with a solvent-based spray I don't see the same increase
in DMax – only 0.1 to 0.3. I need to look into this more deeply,
but 
that is my favourite explanation at the moment.

The coating methods that produce a large increase in DMax do not show 
much improvement by adding dark grey, but the coatings that produce 
little increase in DMax do show some benefit when dark grey is added.

These results do not contradict Clayton Jones' statement: a greater 
increase in DMax could be possible by adding a second black instead 
of dark grey, of course.

Best, Helen