PLATE PROBLEM!!!

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PLATE PROBLEM!!!

Postby Cruzneggy » Wed Feb 22, 2017 11:23 pm

Maybe somebody can help me out I ran the same job with the same aniloxes and with the same ink. Two sets of plates. One set of plates printed good the other set did not. The set that printed good is 10 years old. the one that didn't, had problems with ink transferring. It would make the black text dirty very fast and the reverse bar would get little tiny dots of ink on the edges. Now I know this is a plate problem and ever since I started I've had problems with the simplest of jobs. The plate guy always says it's operator error that I'm not using the right aniloxes or that it's contaminated ink due to poor ink maintenance. Now I can prove it to him. I don't know a lot about plates but I know his suck. What could be causes for crappy plates? Material? Negligence? What is good plate material? Any insight on this would be awesome. Thanks.
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Re: PLATE PROBLEM!!!

Postby bloss22 » Thu Feb 23, 2017 6:26 pm

Do you know what kind of plate material is being used? Also, what process is being used to make the plates? Direct to plate technology or films? Solvent washout or water washout?

My first impression is that the plates are not being dried long enough or not de tacked enough. Do the plates feel sticky? If you put them printed side down on a piece of paper does the paper stick to them?
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Re: PLATE PROBLEM!!!

Postby Cruzneggy » Tue Feb 28, 2017 4:50 am

DuPont plate material. They are using direct to plate, I'm not sure about the washout. As for the tackiness, the plates are not tacky at all.
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Re: PLATE PROBLEM!!!

Postby Fuzz » Wed Mar 01, 2017 3:17 pm

If I were you I'd read any posts on this site about Dupont plates. Especially the FAST system. We had nothing but trouble with them.
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Re: PLATE PROBLEM!!!

Postby richflexo » Wed Mar 08, 2017 1:59 am

Hi Cruz,

Are you saying you have a set of plates that is 10 years old and other is new? Or are they both 10 years old? Just wanted to get that part sorted first because if he used Dupont material from 10 year ago, there's a possibility he was using EXL which was an analogue plate material. The newer plate would be a DPL which is the direct to plate material. If you are printing wide web or narrow web, i'm sure those are the plate materials if they are thinner than .112". If its box or paper he was using TDR 10 years ago and probably using DPC now.

You mentioned the plates are not tacky, good thing you mentioned that. It is likely the problem, you need some tack to the plate. A simple test you should do when you receive plates from your supplier is lay them flat with the mylar down and take a corner edge and just fold it to the other corner and see if the plate grabs each other and then slowly peels off. If the plate doesn't grab it at all, you won't get proper ink transfer and you should ask for new plates. Over dried or over cured plates will do this. He could even have bad bulbs so he's thinking he's drying or curing for the correct amount of time but the UVA and UVC output isn't enough. The post exposing phase is most critical for ink transfer and I would make a guess that this is where the problem is occurring during his plate process. We've run into this problem at our shop before and it turns out our times were correct, but ooops, a whole back of bulbs burned out. It's good practise to get a lighter metre and do weekly if not monthly checks when you start up in the morning.

Hope this helps!
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Re: PLATE PROBLEM!!!

Postby guy de cafmeyer » Mon Mar 13, 2017 1:48 am

richflexo is correct ;
There are two basic things to consider , namely Hardness of plate , and finishing of the plate / tackiness .
One would use a softer plate for spot colours , as a softer plate does tend to accept and transfer ink readily .
One then would use a harder plate for halftones , which gives one a more accurate ink transfer with reduced dot gain .
Either plate requires correct finishing . A finished plate should be slightly tacky , as tackiness is related to surface tension on the surface of the plate , and surface tension determines ink acceptance as well as transfer . To me it sounds like over finishing and your plate manufacturer should decrease both UV A and UV C times ... Hope this helps .
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Re: PLATE PROBLEM!!!

Postby Frank Burgos » Sun Apr 23, 2017 5:58 am

On a positive note, one thing I love about this situation is how it illustrates that the slightest, imperceptible difference in a variable can have a tremendous impact on printing. It also reinforces the importance of documenting every variable you can think of, throughout the workflow. We want to do things the same way, each time, control improvement and have data that we can refer to when challenges like this pop up.

Ain't flexo cool? :smile:
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Re: PLATE PROBLEM!!!

Postby a11an » Wed Apr 26, 2017 3:41 am

Cruzneggy wrote:DuPont plate material. They are using direct to plate, I'm not sure about the washout. As for the tackiness, the plates are not tacky at all.


If this only happens with new plates then try wash the plates before printing.
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Re: PLATE PROBLEM!!!

Postby Frank Burgos » Thu Apr 27, 2017 12:14 pm

Hi Guys and Gals,

Below is a link to a downloadable file I've had for some time. Called "DuPont Process of Use Manual, 2008", it's full of useful information on photopolymer plate-making, troubleshooting, etc.

http://www.flexoexchange.com/downloads/ ... mplete.pdf
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Re: PLATE PROBLEM!!!

Postby Acmegv » Fri Jun 02, 2017 10:49 pm

Is the plate relief on both plates?
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