Well we have just recently changed our sequence from KCMY, to KMCY, the reason for this was the constant switching of the mag and cyan when we encountered blues, which were 100% cyan with a screen of magenta, on gloss coated paper it never traps properly and is all mottled and uneven, switch the mag and cyan and it looks great, my thinking was lets just keep it this way as I can't imagine a scenario where, once in KMCY, I would have to change it back to KCMY in order to solve a trapping issue.
So in 3 months we have had no problems and all our screen build blues and pics with a lot of sky look nice and smooth, does anyone else run this sequence excluslively?
This is not a shot against the printshop I'm referring to below. I've seen what I'm describing at other locations - it's just that I documented this one.
Below is a photo I took of the inks sitting on their respective press units at Integrity Graphics in Windsor, CT, when they were doing one of the runs to develop the characterization data for GRACoL 7.
Note the sequence: KMCY - the one you've switched to.
In keeping with the objective, instrument-based rigors of the process, the GRACoL committee in attendance required that the press operator run "to the numbers" - no proof was used nor available. As press sheets came off the press they were measured and analyzed. There were also some images on the sheet for subjective evaluation.
There was a lot of chatter within the committee group that some of the numbers weren't making sense. Me, just looking at the images, saw a heavy magenta cast. When I looked at the press and saw the ink sequence I suspected that was what was causing the issues. Which I told the group. They disagreed with me, saying that ink sequence would not cause such a problem.
I then went into prepress and asked them to pull a proof. At the time, they were using a Creo Spectrum laminate proofer. The proof looked correct - no magenta cast.
I asked the press operator why they were running KMCY. He seemed to remember that about 6 months earlier they had a problem with blue skies and switched the sequence to fix it and never switched back. I showed the proof to the GRACoL group, explained again the issue. They then asked the press operator to go back to KCMY and run to the appropriate numbers (not looking at the proof) which he did. As soon as he was up to color again, the measured press sheet conformed to the expected numbers. Also no magenta color cast, and it aligned perfectly with the proof.
My point (if you've read this far). For some six months the press operators had been "matching" their proofs using a KMCK ink sequence and compensating for the magenta color cast to match their Spectrum proofs, but at what cost in extended make-ready times, wasted media and, I'll bet, if you closely examine it compromised color or at the very least, not the best color they were capable of.
best, gordo
my print blog here:
Quality In Print
