Printing 2% tint - not holding on plate

[Signature]

I recently printed a job where the sheet did not match the proof. A bar graph looked like it was missing a tint of Cyan. It realistically showed on the Epson proof, but not on sheet. Pressman said it wa the proof that was incorrect. I let it go, only later to check file and found a 2% Cyan tint.

Is it reasonable to expect the shop in this day and age with CTP to hold this 2% tint on the plate or if it cannot to have the proof not show what it cannot print?

[RGPW17100]

What plate are you using?. I know when the Azura plate first came out there were issues as to how well it could print 2 percent and 98 percent. We now use amigo and we are able to print these dots with this plate.

[gordo]

Is it reasonable to expect the shop in this day and age with CTP to hold this 2% tint on the plate or if it cannot to have the proof not show what it cannot print?

Yes.

best, gordon p

[maxon]

I dare say that all platesetters today exposing metal plates be it thermal or violet photopolymer produce 2 to 98 reliably. As a matter of fact as Gordo implied, having - and keeping - a 2 percent highlight comes down to using the platesetter system within specifications - recheck processing conditions (if any), ctp calibration, plate quality and possibly even chemicals in your pressroom insisting on dampening pH measurement.

I believe it's not normal to tweak your proof if the press or plate cannot hold 2 or 3 percent. If the highlight is on your computer monitor it should be on the proof and on press sheet.

[Lukas Engqvist]

In linearisation I have known people to clip low % to avoid boxes around stock images that are not clean white. In Quark there used to be (sorry i am not updated to say if it still is) and option to clip colour info below a certain %.
We never had problems with the Azura plates at 2% and were getting good stable dots even below that, using hybrid raster, the biggest problem getting measuring device to measure correct. We actually did the test with step patches of 0.5% from 5 - 0, our main reason for doing this was to eliminate the risk of ugly cutoffs in gradients.
That being said, we sometimes send jobs to be digitally printed on an indigo, and there we do find cut off in low %, exactly where depends on how fresh the blankets are (new blankets being to hard and giving cutting off highlights more than those that have been worn in. Best results being just before they are worn out ;p ).
That all being said a 2% with a dithered pattern or a coarser screen (lower lpi) will usually show up more consistently. It is not unusual for printers to give in to customers increase lpi beyond their equipments reliable values. Moving from 120 to 200 lpi will make the dot size 0.36, wich ofcourse means if your technology is limited to produce 2% reliably at 120 lpi you may find at 200 lpi you're hitting the limit at between 5-6% (hope i did the math right) and that's not even getting in to the lpi dpi discussion.

[gary b]

I currently agree with the rest of the post except what dpi lpi ect do have a spectrophotometer do know how much plate to press u are currently gaining or losing without knowing your exact situation sounds like u need to get calibrated from press to pre press 2% of cyan on coated or uncoated is going to a big difference as well.

[RobC]

As maxon said Don't forget to check your whole process for any variability before redoing any curves at your RIP. A simple thing like old developer chemistry and can ruin it for you. Has the press changed ink, fountain solution, blanket brand/type, is a different paper being used than what you normally use? It doesn't take much to cause 2-4% dots not to print. In addition to pH of the fountain solution check conductivity as well and make sure it's within the mfg's specificed range. We've found old plate developer chemistry to be the culprit in the past with small dot % and fine line screens which caused us to change the developer more frequently than we originally expected to based on Agfa's recommendations for LAPV plates.

[Signature]

Thanks to all who have replied.

Unfortunately it is not my company.but I suspect a combination of not calibrating at all or infrequently. They do use a Heidelberg Topsetter and I would imagine their plate as well. I allowed them to tell me the 2% was not in the file. I made a bad call on press by listening to pressman.

Bottom line-

In my experience over the years,, it is just another case of a shop slapping ink on paper.

Thanks to all who responded.

[rich apollo]

Is it reasonable to expect the shop in this day and age with CTP to hold this 2% tint on the plate or if it cannot to have the proof not show what it cannot print?

Absolutely.