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?
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.
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.
Samples of bad ink. :rotf:
(https://i.pinimg.com/originals/d8/96/9b/d8969b9b2318bfbed51fa81c06daff45.jpg)
Come on Joe, this is serious you know.....we pump out a lot of junk mail round here!
It's all fun and games until YOU start getting junk mail with poor ink density.. :gom:
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:
How are you measuring the press sheets? Are the densities correct off press?
What standard are the proofs output too?
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.
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.
Do you run GCR?
It shouldn't make a difference... but it IS less ink on the paper?
No GCR. Things just looked washed out. The client isn't color critical but to me it's drifting off quite a bit.
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:
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 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.
:homer:
Quote from: pspdfppdfxhd on March 25, 2021, 10:15:34 AM
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.
Do you have a spectro to read the delta e between the press and the proof for cmyk and your traps?
If the proof is passing gracol on your fiery then it would be something on press or measurement. If press is closed loop color, cameras can go bad for instance.
Quote from: Joe on March 25, 2021, 09:21:10 AM
Samples of bad ink. :rotf:
(https://i.pinimg.com/originals/d8/96/9b/d8969b9b2318bfbed51fa81c06daff45.jpg)
LMFAO!!! A friend of mine wanted that bad leopard tattoo.
We reprofile the presses every 3 months or less. The weather here in Eastern Washington is drastically different each season and we get presses that walk way away from their curves over time.
This might be what's happening on your end. Weather, ambient temperature, humidity all jack with everything.
Packing too. That's important, if their packing more or less than when your curves were made, you'll be getting very different results. If their also running dirty ink, (not completely cleaning fountains when switching from Pantones etc like our guys do) you'll have bad colors too.
Our weather is drastically different up here around Toronto as well.
Since I have been here (22 years) , only one of the presses has been profiled properly, about 5 years ago. We never had a pressman who read densities with color bars until about 7 years ago.
I am wondering how we survived this long. We ran our Azura plates for at least 10 years linear.
Quote from: AaronH on March 25, 2021, 02:01:25 PM
We reprofile the presses every 3 months or less. The weather here in Eastern Washington is drastically different each season and we get presses that walk way away from their curves over time.
This might be what's happening on your end. Weather, ambient temperature, humidity all jack with everything.
Packing too. That's important, if their packing more or less than when your curves were made, you'll be getting very different results. If their also running dirty ink, (not completely cleaning fountains when switching from Pantones etc like our guys do) you'll have bad colors too.
Interesting.... I wonder how many other shops profile their presses and how often.
We profile our color sheetfed press about once a year. Our Epson 9000 proofer uses CGS/Oris Color tuner and a built-in spectro to check each proof to be sure the proofer hasn't drifted. As long as the press can match the proof with the usual ink densities, we can tell that the press hasn't drifted that much, either. Everything is GraCol...I think we use the 2013 version...not positive.
We profile all presses at least one a year to G7 SWOP. We will fingerprint more frequently if we see a drift away from proof or if a consumables change is made.
Our hard proofs are off an Epson P7000 with an inline spctro powered by Fiery XF, each proof has a conformance tag. Only about 1-2% of our work gets an epson proof.
We have Kodak PressProof at all presses
We profile our offset presses about the time when the G7 cert expires. So I think that is every 2-3 years. Our color proofers get profiled when they are purchased, and then they also have inline spectros on them to help to know if they are keeping in line or not. If not, I do an optimization, and we are all good. The 17" we buy a new one every 3 years when the extended warranty runs out. The 42" proofer, we buy when a service call finally costs too much in comparison to a new one.
From the answers I see here it would seem that we are overdue.
Doubt it will happen because of the expense however. :facepalm: