Digital BW, The Print

Olivier, 

> The real issue here is that when I re-load the paper I can see the 
> damage : lots of rubber roll marks on the inked patches. ...

I expected roller and pizza wheel marks also.  The 1800 may be better 
than most printers in that respect.  I've also been using mostly 
Crane Silver Rag for testing, and maybe that paper is more immune to 
them.  In the past and with most printers I would have expected these 
problems to be killers.  I'm not sure why I'm not seeing them.  It 
may be that the matte ink, even with the glop mixed in somewhat to 
hold it down, is such a matte surface still that the marks are not 
showing up.  Where I've seen the problems are with a second overcoat 
of more than 25%.

> > I believe that with the overcoat of Glop we can usually put 
> > down a higher load of black pigment ...

> ... you mean a higher load of 
> pigment in the ink composition, not on the paper, right ?

Maybe both ink limit and composition.  With respect to the ink limit, 
for example, the Crane SR didn't hit a post-overcoat dmax until 120% 
QTR load.  That's a very large amount of ink.

The MIS (Image Specialists) PK for the R1800 is the MIS K4-PK.  It's 
a lower load than the MP or 7600 PK.  It may be that with an 
overcoat, I can go to the higher load ink and get a better dmax.  The 
R2-PK that I've used in the R1800 is half way between these other 
PKs, and it seems to be working fine.  The problem with the higher 
load PKs in new printers shows up as reduced gloss (I think, working 
from memory).  If so, then we might be able to cure that with the 
overcoat.

Clearly, this is still in the experimental stage.


> ... I don't see any benefit in multiple inks 
> at Dmax with MPS, where I see a big plus is that some lighter inks 
> helps separating shadows and smooth the ramp. Provided you find the 
> right mix which is an other story. 

I agree.  With a good pre-linearization ramp in the 90%+ range, I can 
usually get fine shadow separation and still have only K in the 100% 
spot.

Paul        
www.PaulRoark.com