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Author Topic: CMYK ink  (Read 3282 times)

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Offline pspdfppdfxhd

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CMYK ink
« on: March 25, 2021, 10:43:25 AM »
And more on the ongoing saga of pressmen matching proofs, yada, yada, yada.

Has anyone ever ran into bad CMYK ink? I've been noticing the jobs around here are too light. The vast majority of jobs here are not required to match our epson proofer but now and then it comes up. One pressmen matches them pretty good, the other one claims they are out to lunch.

With the addition of a spectrometer and Fiery XF, I have been able to optimize the delta e to about 1.2. We've recieved proofs from outside sources and they look like 99 percent of what we make.

Could ink actually be bad, which would throw the whole thing off obviously. Is there any way of testing the strength of it not only in the solids but in tints as well?



Offline david

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Re: CMYK ink
« Reply #1 on: March 25, 2021, 10:50:24 AM »
short answer...
yes
Ink can be a bad mix, out dated, or somehow gotten "dirty".

any particular brand you guys use?
custom mix or off the shelf?

We use to have a sep. company mix our CMYK and spot inks custom, they had an office in our building and made all our inks in house. If there was a bad batch, they would make more.
Prepress guy - doin' jobs one at a time
www.texasgraphics.com

Offline pspdfppdfxhd

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Re: CMYK ink
« Reply #2 on: March 25, 2021, 10:53:39 AM »
Thanks, but how would you test it across the range? I mean different screen values. I understand how the spectro on the epson works but have no understanding how press ink can vary.

Offline Joe

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Re: CMYK ink
« Reply #3 on: March 25, 2021, 11:21:10 AM »
Samples of bad ink. :rotf:

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Offline pspdfppdfxhd

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Re: CMYK ink
« Reply #4 on: March 25, 2021, 11:25:57 AM »
Come on Joe, this is serious you know.....we pump out a lot of junk mail round here!

Offline pspdfppdfxhd

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Re: CMYK ink
« Reply #5 on: March 25, 2021, 11:27:44 AM »
It's all fun and games until YOU start getting junk mail with poor ink density.. :gom:

Offline born2print

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Re: CMYK ink
« Reply #6 on: March 25, 2021, 11:51:53 AM »
Don't forget to keep stock in mind, as ink seems pretty consistent across brands and even grades.
We had a job yesterday that was a solid with 60% underrun... should be able to run that all day every day...
but the pressroom has struggled with it so for just this job's 2 items we made both hits 100%.
I would have to say, the olive drab Pantone ink is a suspect but seems unlikely to be the culprit. I wonder if it's the stock... 60# offset I think
we run that stock a lot but not with full coverage.
 :wtf:
He stated their PDF's are 99.9% accurate and I replied we prefer 100% accuracy.

Offline johnny_jay

Re: CMYK ink
« Reply #7 on: March 25, 2021, 11:53:58 AM »
How are you measuring the press sheets? Are the densities correct off press?

What standard are the proofs output too?
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Offline pspdfppdfxhd

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Re: CMYK ink
« Reply #8 on: March 25, 2021, 12:15:34 PM »
Apparently the pressmen are reading the densities properly on the color bars. But we only have solid 100% circles on them. Not sure about the paper. Think it's been the same year in and year out but things are getting lighter.

The proof setup is for GRACoL2006_Coated1v2 with a contract proof tolerance set ISO 12647-7:2013. Through EFI and the delta E has been improved to 1.2 ave, 2.2 max cmyk all patches.






Offline pspdfppdfxhd

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Re: CMYK ink
« Reply #9 on: March 25, 2021, 12:30:24 PM »
The printer that says the proof is out to lunch measures those solid circles till he gets the right density and runs the job. There's no wiggle room there, just hit the numbers and go.

The press was profiled to the plate curves a few years ago and things were going better for a while, I have no idea if he's keeping his press up to spec. as well. He says so.

It's hard to talk with him about it, he seems to know it all. I think its a worldwide thing about pressmen knowing it all. Like the coronavirus, it has spread world wide.


Offline born2print

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Re: CMYK ink
« Reply #10 on: March 25, 2021, 12:46:52 PM »
Do you run GCR?
It shouldn't make a difference... but it IS less ink on the paper?
He stated their PDF's are 99.9% accurate and I replied we prefer 100% accuracy.

Offline pspdfppdfxhd

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Re: CMYK ink
« Reply #11 on: March 25, 2021, 12:56:04 PM »
No GCR. Things just looked washed out. The client isn't color critical but to me it's drifting off quite a bit.



Offline born2print

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Re: CMYK ink
« Reply #12 on: March 25, 2021, 01:06:28 PM »
Press chemistry? Calcification or some other thing I don't know much about....
different presses = different fountain maintenance?
blanket condition / packing?

just grabbing for straws in case something randomly makes a bell ring :shrug:
He stated their PDF's are 99.9% accurate and I replied we prefer 100% accuracy.

Offline born2print

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Re: CMYK ink
« Reply #13 on: March 25, 2021, 01:08:15 PM »
Try auditing the densitometer? They need to be calibrated periodically... see if you get the same readings.
Switch with a press that has less trouble.
Maybe they are getting good / standard density readings that are false and therefore they are running light?
He stated their PDF's are 99.9% accurate and I replied we prefer 100% accuracy.

Offline pspdfppdfxhd

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Re: CMYK ink
« Reply #14 on: March 25, 2021, 01:40:33 PM »
He claims his end is all good. If the ink is ok I wonder if the whole press has to be re-profiled.

Another pressman here who will try and match color, running the ink heavier or whatever he does, changed a blanket a while ago back and his color went off. The owner "eye-balled" where to modify the plate curve and they were happy.