Digital BW, The Print

"ragarecords" <raga@...> wrote:

A few more thoughts came to mind on the issues you raised.

> ... I am giving up on getting a 2200 to run with a MIS UT7 CFS...

Was the ink level of the CFS kept above the level of the print head?  The problems you report sound like they could be caused by the system syphoning the ink back into the tanks because they are lower than the head.

>... I will adopt Paul's new C-6 setup ...
> 
> Any recomendations on the 7th channel? Paul's recipe uses 
> the M dilution twice. However profiling from scratch in QTR 
> will be easier for me if I don't do that.

It's true that QTR's standard single partition profiling can't handle 2 inks of the same density.  However, often smoothness can be increased if there are multiple, overlapping channels and partitions.  I typically do this by having separate profiles and running them together with the sliders.  I think it might be easier to treat some of the inks as toners in QTR.  This would allow quicker re-linearizing.  I have not tested this approach, but it ought to be workable.  

Note that the Epson driver does some of this automatically.  That is, you have 3 color channels and a separate gray channel with the K2 and K3 machines.  So, if the inkset is made to work with the Epson driver, that plus QTR's Create ICC gives a very simple, very smooth output.  I think having a system that can run with the Epson driver is an important attribute of any inkset.  I'm working with a person whose image is mostly a perfectly smooth gradient, and the Epson driver with QTR's ICC is producing the smoothest, best image of any approach I've tested.  

With respect to using the Epson driver, when I set up the Y=EZY carbon approach for the 2400, the 13.5% (equivalent) density of the EZ ink actually produced a better print than a very light carbon in the Y position.  That Y position is, in effect, crossed over to the black as are the other color channels.  So, the EZ density, which is what I found long ago worked best if there is only a single density midtone in a C88 type quad setup, also may work best for the Y position in a hextone or higher system when it is run all the way to the black cross-over.  So, using this density in the Y position is someting I'm going to explore.

The 220 "R2" system was the "EZ" system for hextone printers -- that is, used the least number of different densities and ran very well with the Epson driver with no separate profiles at all.  This system used only 2 midtone densities -- equivalent to the cyan channel of Eboni-6 (30% and 9%).  In the R2 setup the ligher midtone is used for Y, LM, and LC, and the darker midtone is used in the C and M positions.  The standard Eboni-6 dilutions (30, 18, 9, 6, & 2) print lighter than optimum with the Epson driver.  It may be that increasing the average densities would work better if the Epson driver is used.  On the other hand, the R2 system did not quite give totally dotless highlights if examined with a loupe.  So, at least one ligher ink for that position might improve the system.  But the R2 approach was about simplicity.

At any rate, what I've found is that, QTR profiling issues aside, having multiple inks of the same density gives results with about the same advantages as having inks of different densities, as long as there are enough light and dark inks in the mix. For example, if the system shows some microbanding in the midtones, a duplicate midtone ink running an additional jet there will help just as much as having one that is slighly different in density.  So, having multiple inks of the same density may give smoothness with more simplicity than having lots of different densities.  The profiles just have to be set up correctly.

Paul
www.PaulRoark.com