Lightfast inks

[Prepper]

We are having trouble reprinting a job that we've successfully printed in 2009 and reprinted in 2014. We used lightfast inks and are printing on our half-size Heidelberg. These are photos of 8x10, 11x14 and 16x20. Original 2009 printing was regular 175lpi screening, 2014 reprint was FM screening with a different brand of lightfast inks and it matched the 2009 printing really, really well, even with different inks and screening. Now with the same inks as 2014 but different paper (original paper no longer available) we cannot get it to work no matter what inks or papers we try. I am using our regular G7 profile which is what we used in 2009 also. The file we're printing is the very same plate PDF file as printed in 2009 and 2014, so very same profile, dot percentages. We are printing on a silk or dull 80# cover and using aqueous matte coating.

My question is would lightfast inks, because of the very different color of pigments, especially in the magenta it seems, require a custom CMYK profile of their own? Or, would they require a different sequence? We print KCMY. The problem we're having looks like a trapping issue to me. A very dark area of the photo in the file is 64-66-69-89 CMYK and is coming out green looking this time and while a very dark color was a brownish tinge to it in the proof and past prints. The traps are: MY 85% dE 5.73, CY 90% dE 10.7, CM 92% dE 11.42.

We've tried various curves, old ones from 2014, new ones made this time for this ink and paper, no curves and get pretty much the same results. Just lighter or darker. Where should we go next? Custom profile is what I'm leaning to right now. Pressman mentioned checking breakaways but said he's pretty sure that's not an issue. We've spent 2 days on this already.

I might add that we also printed posters a couple months ago with these same inks and paper, that while not a perfect match to our proof were acceptable and good, about 50,000 of them.

 

[ponnapati123]

There are many factors which effect the print quality. As you are saying all machine parameters are same and you did calibration for machine it seems problem is something other than printing machine. Check dot reproduction in your plate using plate scope, then check the inks whether any changes they did on inks. Check prepress color correction settings and conversion of RGB to CMYK. If you are using color saving softwares like GCR or UCR might be the problem with the software. Verify all process step by step then at some point you will get the cause.

 

[aqazi81]

How can you print with same data on two different papers to produce the same results?

 

[D Ink Man]

I will say that the trap dE's are very high, even for process inks.

You may have to revert to the old fashioned way of MANual manipulation to achieve pleasing reproduction.

If possible (ha ha), get your ink supplier to pull single color proofs of each ink, as well as 2/C traps of the inks you are using, of course on the actual job stock. Have them measure dE's of each as well as simple hue error/grayness of the singles on the densitometer. This previously was an easy task to figure out when a printer and an ink supplier of technical nature were in harmonious collaboration. Good luck!

D Ink Man

 

[buckeye]

I'm with aqazi81, that's enough of a variable in itself.

 

[D Ink Man]

You're right Buckeye; who the hell could expect that kind of service nowadays.

D

 

[Prepper]

How can you print with same data on two different papers to produce the same results?

So I suppose you have custom curves for every brand\supplier of 80# gloss cover you run? And silk\dull?

Same data (curves) I'm assuming is what you're referring to, on same type of paper, gloss, dull, etc. is usually the norm is it not?

We use several different paper suppliers and we do get similar results on most gloss papers and tweak curves on the fly with pressSIGN IF they fall outside the tolerances. Although I do preach sticking with one house paper and not changing anything as long as it's working and no economic reasons to, but that's a really hard sell to some who like to change things up every other day because they don't think it really matters.

I asked for info on lightfast inks, doesn't seem anyone has any experience in that area.

We did put it back on press this morning, switching to 175lpi instead of 20micron FM and it worked really well. Got the job done. Pressman did do breakaways on the Y unit because it was looking like the Y just wasn't laying down right or was filling in in some areas but they said they didn't make any big changes, just some very minor ones. ?

Moving on...thanks

 

[turbotom1052]

So I suppose you have custom curves for every brand\supplier of 80# gloss cover you run? And silk\dull?

Same data (curves) I'm assuming is what you're referring to, on same type of paper, gloss, dull, etc. is usually the norm is it not?

We use several different paper suppliers and we do get similar results on most gloss papers and tweak curves on the fly with pressSIGN IF they fall outside the tolerances. Although I do preach sticking with one house paper and not changing anything as long as it's working and no economic reasons to, but that's a really hard sell to some who like to change things up every other day because they don't think it really matters.

I asked for info on lightfast inks, doesn't seem anyone has any experience in that area.

We did put it back on press this morning, switching to 175lpi instead of 20micron FM and it worked really well. Got the job done. Pressman did do breakaways on the Y unit because it was looking like the Y just wasn't laying down right or was filling in in some areas but they said they didn't make any big changes, just some very minor ones. ?

Moving on...thanks

were they viewing the yellow singles through a Kokomo filter. Without this filter it would be pretty difficult to see just what the yellow printer was doing?