Digital BW, The Print

>With the 
> Eboni in the Magenta head I get a max density of 1.69 while it 
> achieved1.61 in the Black head. 

Ernst,

good point. In fact the 7500 I used to test the Ebony had the 
black loaded in the Cyan head. I would have thought the Black
head gives the best black as it has higher current - but I guess
not. Variations like that, however, seem big enough to invalidate
any attempt at canned profiles. I thought these machines
were far more consistent  (at least from one printer to another).




>With the other ink distribution on the 9000 I also think 
> that a boost of the next grey ink on the black also depends on 
> which channel is used for the black and the grey. My guess is 
> that the Black channel lays down the last ink layer and when that 
> ink isn't black ink like in my case the next grey will be on top 
> of the black and the density drops.


Funny you should mention that. I tested a beta driver that
deliberately switched the printing order at the head, just to test
this theory (dark gray first, black last).
I  measured no change in the dmax.
That was on a 1280, however, where - maybe - Ebony 
doesn't do too well for dmax in the first place.
Also did a double pass with just black on the same paper.
The second pass resulted in less dmax than either of the
passes alone. That was on EEM. I suspect this may vary by
paper type.




> The pigment in that grey is 
> not the Eboni kind and gives more reflection than the Eboni 
> pigment. If I measure the unlinearised BO greyramp of the Eboni 
> then I see no Dmax drop at the highest inkload.

I believe BO will always give higher dmax with pigments, possibly
because of paper load issues. On any printer, the unlinearized
black ramp ends up with higher dmax than the profiled ramp where
grays come in. I tend to think it's about how wet the paper gets and
whether it can hold equally the black and the gray. By bringing
in a gray, it accepts less of the black, hence its tricky to profile
quad shadows.


Antonis