Digital BW, The Print

"Terry" <TerryGls@...> wrote:
 
> "pr_roark" <paul.roark@> wrote: ... 
> > If the actual dmax is at 70 but the slope of the curve is very low between 60 and 70 -- that is, they are barely separated -- then I'd use 60 as the K limit and put 70 in the black boost box.  (Note that there may be other factors like pizza wheel issues, but I'm not considering that at the moment.)  


> Paul, You mention "actual Dmax" … I think I'm understanding part of your point except in one area of "visual PK max black" or "actual Dmax."  My 100% Ink Sep Page print out for the PK ink shows actual densitometer readings as follows: 60%-2.05, 65%-2.11, 70%-2.2, 75%-2.28, 80%-2.34, 85%-2.4, 90%-2.40, 95%-2.51, and 100%-2.53.

> As mentioned before the 60% square visually looks as black as the 65%, 70% all the way to 100%..
> 
> So, if I follow your point and set the PK Ink Limit to 60% and Black Boost to 70%, my measured density will be 2.2 but not near the 2.53 Dmax black possible "in theory."

If the black boost is set to 70, you're get your 2.2 density with a file input of 100%.  If you set the black boost to 100, you'll get 2.53.  As noted, you may run into other issues like more pizza wheel marks due to the ink not being very dry by the time it hits the exit rollers.

I like to use the QTR Black Boost for several reasons.  I think it makes for a better partitioning when you use a K limit that is closer to the more linear parts of the black curve.  Also, you can change the black boost without messing up the rest of the profile.

... 
> >I use a loupe to see when the bleed starts to become an issue, ...

> What do you mean by "bleed" and what are you looking for with the loupe?

It'll look like roughness in the print.  The inkjet coatings are made to pull the water straight down into the paper as opposed to wicking out laterally across the paper fibers.  With glossy paper the barrier between the coating and the paper limits how much water the coating can pull away from the surface, thus excessive fluid will start to flow laterally and also simply stay wet on the surface.  In matte inkjet papers the paper base is part of the reservoir for the water.  So, it's less of a problem.  

With the Arches watercolor paper I'm starting to use there is no inkjet coating.  As such, I have to use very low midtone ink limits to avoid this bleed and roughness problem.   The ink just starts to wick out across the fibers on the surface of the paper, and the image starts to look very rough.  On the other hand for the black dmax with Arches, I pour on lots of ink.  The deep shadow hide the bleed and roughness and I don't have a pizza wheel problem.  So, with Arches the Epson driver does not work because it sets too high an ink limit for the midtones and too low a limit for the black.  QTR or other rip is essential for good printing.

Paul
www.PaulRoark.com