We have a group coming in to "G7 us" for reasons unknown as we already have been through the process.
I didn't take part to much in the process (hey someones gotta get the work out) but do understand the basics about G7's methodology about gray balance.
What I'm looking for are questions specific to G7 to hurl at the folks coming in to see their level of knowledge.
Here's a question, trying to simulate Gracol 2007 grade 1
what do I do if - cmyk hits the lab values, -the gray balance hits the gray lab numbers, but after measuring the IT874, the measured data is close to spec, but the boss want's it tighter
If you hit the Solid L*A*B*s and Grays what was your DeltaE comparing the IT87/4 to the Characterization data set ?
Whats the definition of "close" ? And what did you use to compare ?
So you hit the numbers exactly on both the linear and curved run ?
And it doesnt look perfect ?
Getting the press to run the second set of plates the same way as the first is one of the most difficult parts, if its
not matching to your expectations I would start there.
Read your P2P targets of the second run and see if your curves did exactly what they were supposed to.
Do you start with plates that have a curve applied to linearize them or with the plates uncalibrated (no curve aplied)?
Do you test the rheology of the inks prior to the G7 process or is that included in the process?
Do you test the mechanical condition of the press prior to the G7 process or is that included in the process?
Do you have any before and after examples from other customers? (I.e. press to proof alignment old way and press to proof alignment via G7)
Do you have any samples that show presswork from different printshops that show how close the alignment is using the G7 process.
Does 3/C gray balance go from 0% to 100% values and if not at which point does ink trapping additivity failure occur and what do you do about it?
Because of the variance of UV optical brightners used in press sheets, is it possible to align inkjet proof and press sheet if you are not proofing on the actual press sheet paper? What do you do about that?
Have there been any substansive industry technical studies/reports (e.g. GATF, TAGA, etc.) on the use of gray balance specifically on press (as opposed to proofs and/or scanniing)? If so, provide the references.
Nice ones Gordon...sure to keep them on they're toes.
How about...
Can I use the same plates curves with different paper stocks (going from coated grade #1 to coated grade 3 or 5 for example)?
How about for different line screens or dot shapes (going from 150 to 175 or 200l/s)?
Have you calibrated stochastic or hybrid screening towards G7 and what are the differences compared to AM?
What kind of differences should we expect when calibrating to uncoated paper ?
If we change ink to another ISO 2846 compliant in set, will we need to rebuild plate curves?
What do you reccommend for color separation when deviating from typical paper/screening on press?
What are some good tolerances for HC, HR and SC?
What are HC, HR and SC ?
Just how many of these G7 thingies have you done anyhow?
You're charging me HOW MUCH?
What is the Average Airspeed Velocity of an Unladen Swallow?
Some more: If I'm already printing to ISO12647, will I see a difference that's worth any money?
Does Mike E. have first hand knowledge that two inks that are both ISO2846, which some think is as wide as a barn door, will need different G7 curves?
Is Gordon's ink rheology question important? You just change the curves to line up the gray balance, don't you?
Do you do the G7 thing with UV and aqueous coating on the image? Hope it's not too late to ask more questions about G7...I think TAGA/PIA/'GATF already have stuff on this that you can read to get even more confused.
John Lind
724-776-4718
Cranberry Township PA
What are some good G7 questions?
Linear Mode
