Here is a brief update on my effort to create a good working profile for the Epson 7600 with the K7 Selenium inkset from InkjetMall installed. My original intention was to edit one of the Cone Profiles for paper to work with my digital negative process but then I discovered that the Cone Profiles couldnt be edited with regular QTR tools. That was quite a surprise and rather threw me for a loop. But then I decided to contact Ben Altman with whom I had briefly worked on another QTR project a couple of years ago to see if he would look at one of the Cone profiles to see if there was any way I could load edit it. That proved to be impossible, but Ben offered to collaborate with me in creating a profile, an offer that I readily accepted.
So we started to work. First I printed an Ink Separation sheet for Ben to record, and then several preliminary trials, then finally a series of profiles in an effort to linearize a digital negative to my carbon process. We encountered a brief snag because Bens step wedges were in RGB Mode and I wanted to print in Grayscale 2.2, first because this is the recommended Mode for QTR and K7, and second, printing in Grayscale saves a lot of memory, important with very large files. Ben re-did the wedges in
Grayscale, as there is no simple conversion.
Well, after much work we finally got a profile that prints a virtually straight line and linear print from a digital negative. I just made my first carbon transfer print from this profile, and it has beautiful range of tones from the highest highlights to the deepest shadows, with very nice grain.
That is my side of the story.
Sandy
Ben adds the following.
Working with Sandy on this project has been a pleasure, and very instructive
as I develop my Excel QTR programming tools. It is quite something, I think,
that we were able to figure this out - Sandy printing tests from a program
he has not seen, providing measurements and feedback, and me programming for a printer I've never used, an inkset I've never seen, and a wet process I don't know. We never spoke on the phone the entire time!
The Cone K7 Selenium inkset, when used for an ultraviolet process, turns out
to have a very wide range of inks. The Matt Black is a very powerful
blocker, and even the second shade is substantially more dense than say the
Epson Photo Black for a 3800. At the other end of the scale the three
weakest blockers do little, or in one case nothing. I used them in the
profile mainly because Sandy found the nozzles were clogging if they were
left idle.
Although the OHP will absorb a large amount of this ink, we found that at
higher volumes we were getting peculiar artifacts. My step wedge consists of
separate squares on a mid-gray background, with a narrow white border. The
artifact is an "echo" of the border just inside the square - a line of
lighter gray in the tone of some of the squares. Also some ink combinations
were quite grainy. We eventually found our way to something that avoids bothproblems. We also had a still-unexplained change of density at one point, which required adding in a small amount of Matt Black to restore the density
- and more trial profiles.
The profile that we ended up with is very linear - about as close as one can
get within the "noise" of a hand-coated process. Sandy's Carbon process
does turn out to have a small but noticeable shoulder and toe; the profile
linearizes that nicely. I'm working on some programming to further smooth
the profiles, and to speed up the whole rigamarole.
We hope to do more tests in a few weeks time, and will post results.
Also important is a work-flow that zeros-in on the best ink combos. I'm getting close. The project with Sandy has been a good exercise in what is really needed in the work-flow.