Hi Richard,
The "Carbon Variable Tone" beta I'm experimenting with is all 100% "Eboni" carbon, and all inks are dilutions of "Eboni-6" but with the new (potentially) Eboni. I have diluted them with my generic c6c base. So, the approach is or should be easily available to the those who are interested. I'll test whatever ink MIS settles on for it's MK. They have my feedback on this STS version (which is a mixed bag, but on net worth my paying the bucks and taking the time to scale my 7800 to it).
Part of my testing, and this new ink arrangement obviously came out of my need to test what appeared to be the "new" Eboni. I need ink for my own printing, and when a new supplier takes over, I need to know what we're dealing with. As long as I'm going to have to change and re-profile, I might as well explore the alternatives, and this "variable tone" carbon approach has some aspects that really appeal to me.
The variability comes from the different tones that the carbon prints with when it is at different dilutions. The paper characteristics are one variable, but, in general for inkjet matte paper, 100% Eboni MK is almost dead neutral. (And that is a big reason that carbon was selected by me and Bob Zeiss originally.) The dilute Eboni carbon is warmer. The warmth peaks out at the "M"/"LK" densities (18%). Eb6-Y (2%) can be quite neutral on a minority of inkjet papers.
So, the profiles don't juggle between 2 different carbons, and there is no "toner" with color inks in this inkset. The profiles use different combinations of dilutions of Eboni to change the warmth of the print.
This can be done with either QTR or the Epson driver (in combination with Photoshop image adjustment curves, best used in linearized ICCs made with QTR's Create ICC-RGB. (That opens up a color managed Windows workflow.)
I happen to think it is important that, particularly at the desktop level, an inkset print well with the Epson driver, even when no profile at all is selected by the photographer. For wide format, I'm less concerned, but surprisingly, there are very good photographers with wide format printers who simply use the Epson driver with Eboni-6. (Those of us who enjoy profiling are a very small minority.) With the 1.5 pl desktop printers, the MK in the Y position is hidden very well. With wide format printers, that K is going to be visible. The traditional Eboni-6 arrangement is not being abandoned by me; the same inks are used in both setups -- even the same carts on the 1400 family platform since the chips are not position specific.
One of the most interesting profiles to look at is the QTR "Cool-smoother" profile. There I use 2 MKs. That gets rid of microbanding, but is obviously not as smooth as a multi-dilution, partitioned inkset. Note that I draw the K curves manually. This is easy, and manual curves are going to play an important role is where I'm going because they can fine-tune a profile even after it is linearized.
Part of the 3-MK and now 2MK approach is to stagger the starting points of the MK inks. It's smoother that way.
To smooth the 2MK graininess -- mostly in the midtones, probably due to the dithering, not the ink dots themselves -- I wanted to use the ink that would warm the print the least. So, I turned to the 2% dilution. Most inkjet papers (not watercolor papers) can hold an enormous load of this dilute ink. Also, the MK channels pour relatively little water into the paper. So, I can crank up the 2% about as high as I want to, depending on how smooth I think the print needs to be. I'm not sure I've ever seen banding with the 2% ink. So this profile just lays down a rather heavy load of gray that acts to reduce the contrast of the 2MK stochastic/random dithering pattern.
I am definitely not a slave to pixel peeping the highlights for dots. That is simply not what I see people react to in B&W photography. As long as the pattern is not a distraction from the photo, I don't care how many inks are used. If 3 makes the best neutral print for the image I'm working on, then I don't care that 3 other inks are ignored and not used. On the other hand, if I need more smoothness, I just pull in the fully partitioned profile and use QTR sliders to balance smoothness with print tone.
Watecolor papers are a different breed. The use of the 2 MKs seems to actually increase the potential maximum dmax. Part of this may be from the ability to go over the 100% ink load of QTR. Watercolor papers are made to take a lot of water. Actually, what I find with Arches is that the dot gain or wicking of the ink out along the paper fibers is not bad with the MK, but quite bad with the 2% K. With the test strips I have, I look at the numbers/text to see what is happening to the edges. The Cone profiling that at least used to use light inks in the 100% black position actually had signigicantly more of a problem than I'm seeing. I avoid light inks at the end of the scale, and the watercolor papers can sometimes take an enormous load there.
Paul