Digital BW, The Print

> We're using Glop (the MIS version seems to do a much better job 
than 
> Epson's according to Carl's experiments) both in the first pass and 
> as a second-pass overcoat.

Fine, but the issue is reloading the paper as I see it.

> We tried various approaches -- no Glop at first, a flat amount, and 
> various curves for the Glop during the first pass.  The reasons for 
> the Glop during the first pass are to help "nail" down the matte 
ink 
> at least somewhat to avoid abraision marks and to result in an even 
> final gloss.  Particularly before we were using PK, the end point 
> required a very large load of Glop to get an even gloss.  With PK, 
> the matte-compatible (not glossy) inks still need a relatively 
heavy 
> load of Glop to avoid a gloss differential when the very glossy PK 
> takes over.  It'll take a few iterations at the cross-over point to 
> get that transition looking good.

As you mentionned further down I use Piezo MPS. For some reasons, 
I "feel" K is different from the other inks, but overall it's a 
glossy set.

> On the other hand, I think it's possible, if PK is used, that one 
> could use no glop at first and just pass the print through a second 
> pass -- maybe using a different printer --  for the glop overcoat.  
> But the risks of marks and gloss differential would be increased.  

Exactly.

> With a K6 setup, I think the main thing you'd have to do is 
> substitute a PK for the combination of inks Jon uses at the dark 
> end.  (Note in the k6-7 test strips I've seen, the 100% is already 
> bleeding badly from overloading.)

I see both over-inking and partitionning with QTR as an issue with K7 
MPS that further complicates GO implementation. The multi-pass is the 
straightforward way, but the single pass can help saving marks and 
scratches on the paper.
 
> In my latest QTR profile, the Glop curve is as follows: 0;0	25;5
> 	50;10	75;24	80;27	85;30	90;30	92.5;27	95;22	100;0

That a very heavy load at the dark end that tends to indicate a 
single pass is hopeless.
	
> I split this between 2 channels limited to 50% each.
> 
> My PK curve is as follows: 0;0	10;1	20;1.5	30;1.5	40;2
	50;1.5
> 	60;1.5	65;2	70;1.5	75;1	80;4.25	85;8	90;15
> 	92.5;22	95;35	98;60	100;100	  (Ink limit 100)
> 
> Note that with the overcoat, the PK does not reach it's dmax until 
> beyond 100%.  But the marginal increase may not be worth the effort 
> it takes to hide the gloss differential.

That's to hide mat ink (sorry I'm not sure I can follow it all) ?
 
> In general, I think it's a mistake to have any 
> other inks in the 100% spot aside from the MK or PK.

Do you care to expand on this.
I have experienced with MPS that some lighter dilution while not 
really improving Dmax helps separating shadows in the 95-100%.

> The second pass is done with a 100% Glop overcoat, split between 2 
> channels.  With the 1800 I was able to see some microbanding in the 
> glop if only one channel was used.  That would probably not happen 
in 
> a 3.5 pl printer.

I'm sure the second pass is a nice finishing. But this means one 
doesn't care about registration (fine) but also that the first pass 
would have protected the print ? Why not go the PrintShield route for 
the final finishing if the first GO pass does the job ?

> So, bottom line, with Piezo (I assume that is what you're using), I 

Yes as I said the MPS version.

> I hope this is somewhat responsive to the question.
> 
This has been and beyond expectations. Thanks.

Olivier