Blinding problem

[jzaloom]

Untreated water is one of the causes for plate blinding. By untreated I mean no Deionization or Reverse osmois treatment.The calcium in the water needs to be removed because it will form insoluble salts when emulsified with the ink. These salts deposit on the image and render the image non ink receptive. Also calcium in the paper that is not chelated will form insoluble salts( the job of a good fountain solution).
Adding chemicals to treat the water is a hit or miss in controlling calcium. Depending on where the source of the water comes from will determine the amount of calcium in it. I highly recommend that an in-house water treatment system be used along with a good fountain solution.

 

[Hessel]

Well the problem is we are not the only company with these problems. There are some in the Netherlands, Belgium, Germany, Spain. And some have a 10.000 liter tank , some use normal water. We also tested with this.
Today i already saw the lines in the plate before printing. Very strange.

Last week we tested with 1 year old chemicals Agfa had in stock and the result was mindblowing. The solids on the plate were black as it should be and not gray. The print was much better, less waste starting up and a visible much sharper print. So Agfa's comment nothing has changed since 3 years in the chemicals can also be flushed down the drain.
Tonight we will do a 170K production on Fuji plates. If there is no blinding tonight we know the cause of our problem.

 

[Hessel]

Here's an image of the difference

 

[Lukas Engqvist]

Be iinterested to know if it wsa the old chemicals or the fact that the chemistry was remixed. Using a fresh batch of new chemistry would have the same effect? If so then how is your chemistry re-plenished?

 

[Hessel]

The left plate (best result) was with the old chemistry. Agfa keeps 10 x 20 liter cans on stock of each batch. So thats why they could send us this. The current chemistry is the plate on the right.

If i drain all chemistry and renew it with my current chemistry it still does not give the same result as the old chemistry.

 

[Lukas Engqvist]

Probably somthing that kills the environment in the old stuff ;P (chemistry that is replaced by "green" "equivalents")

 

[Green Printer]

We had bad chemistry a few years ago. Its was traced to an Agfa contract chemical manufacturer. Of course there wasn't chemistry problems according to Agfa. After the problem was fixed then there was admittance of a chemical problem. Keep on it.

 

[Green Printer]

Also there are chemicals in the chemistry that make the plates INK RECEPTIVE.

 

[Hessel]

New developement:

Agfa and Fuji polymer plates also blinded. We will test Kodac Thermal plates soon but things are pointing towards the Flint ink more and more in my opinion.

 

[Hessel]

We narrowed the options to the plate thickness. Last 5 weeks the problem was gone. When i measured the plate thickness it was 0.28mm. This week the blinding appeard again on 027mm thick plates. Goss tells me the minumum has to be 0.28mm. The fuli plates we tested were also 0.27mm. So well wait and see.

 

[Lukas Engqvist]

Keep track of the impression. Don't know the terminolgy in english but the plate to roller. Especially if you already see that plate thickness is one of the players in the game.

 

[Airguide]

I also had a problem recently with the image disappearing off the plate after a few 100 sheets were run, and the images weren't dark on the plate like they were supposed to be from the start. The problem ended up being a bad motor in our plate processor that didn't circulate the developer properly and one of the tubes were partially blocked. After we fixed that we still had the problem of the image disappearing, but it didn't do so until about 10,000 sheets. So we raised the developer tank temperature from 25 degrees Celsius to 30 degrees Celsius and almost doubled the speed of the processor, so the plate would spend less time in the developer tank. That fixed our problem.

 

[Hessel]

Update:

We still have problems with blinding. As you can see on the picture the repeating lines are already on the Lap-v plates out of the box.
We did a Kodak test on Thermal news Gold and no problems.

Are there more Lap-v users out there with problems?

 

[larrysison]

Hi Hessel.

You may want to contact Carlo Van Spijker, European Technical Service Director News Ink of Flint. He's from Holland, as well.

Working with Carlo are Wim Decaluwe (formerly of Ifra) and Paul Kellett (Blanket expert). I'm sure they will be able to tell you exactly what's causing your problem. You can call him thru: +44(0)161-776-6810 or +44(0)7714-154622.

Kindly send him my regards.

Larry Sison
Ugra Certified Expert
Dammam, Saudi Arabia

 

[Hessel]

They visit our site regular. They did a lot of tests and put a plate under a microscope and found isseus in the plate. But Agfa won't give in.

 

[Prepper]

Re: Blinding

Re: Blinding

For what its worth, we've had blinding issues with the Fuji Ecomaxx-T plates here and rollup problems on press, so we tried processing them off press and the blinding problems went away, problem with processor a couple weeks later so went back to developing on press and blinding problems showed up again. Same paper, inks, solution, press etc, and processing offline no blinding, on press blinding. Why? We don't know and there are way too many variables for anyone to put their finger on anything definite yet. We went thru all the recommendations on solutions, temps, etc and couldn't make it work for whatever reason, some may have been operator error, but my opinion is we need a bulletproof plate when it hits the press, as much as possible with no concerns about whether it will clean out all the way or partially, sometime operators don't notice a partial cleanout, whether it will blind at some point or not, or how long it will sit before being run and whether it was kept in the dark or not, etc.

I also saw another post where someone said they changed paper and the blinding went away, went back to the other paper at end of run and blinding came back within 500 sheets.

Don't know what it is but it doesn't seem to be just Agfa plates as you've found but I do know that our blinding problem went away when we process these offline prior to press, just haven't found a solid way yet that works to do that (processor) either.

 

[Printservedigital]

Hessel I've seen that before on different agfa plates.

Please confirm though Is that plate the same travel of direction through your processor? Please indicate direction of travel through your processor!!!

We resolved it for a national newspaper title.

 

[Printservedigital]

Today i already saw the lines in the plate before printing. Very strange.

It's not a press issue then

Like I said Ive seen this before.

 

[Hessel]

I can see it in all the plates out of the box. One batch worse than the other.

 

[Printservedigital]

have you tried intercepting a plate after the platesetter (Before any preheat) and then soaking it in developer for 30 seconds moving it around?