Plates Not Holding Ink properly

[jrrowellprinting]

We use Agfa LAP-V plates run through a Raptor Pro85s plate processor that is badly in need of new rollers. My co-worker keeps the machine clean, but lately we have had the issue where the plates come out looking not so great with a wavy look to them - for example on the left of the plate the 100% blocks on the color bar look darker than in the middle of the plate, but our reading is that they are 100% all the way across the plate. Once the plates are on the press, my pressman has to run very heavy ink coverage to make the final product look acceptable. We are still up and running, but it is causing my pressmen to be very angry and I don't like it all. Forgive me, I am not an expert in the plate processing department so any answer needs to be dumbed down for me to understand. I have called for service but like to know what I am dealing with before having a service tech come out. Any ideas of what our problem is would be helpful!

[REYES1377]

Our company uses the same AGFA set up. There maybe two problems. 1) check the lazer intensity. Make sure the 50% are comming out at 50%, + or - 1 or 2 %. 2) Clean the mirrors!! This is most likely to create that problem.

[maxon]

If the wavy appearance got worse over a short period of time e.g. hours, max. next day you should do a quick chemistry change before the service rep arrives on site. And yes, a good cleaning of the optics may be required - that would explain the left to side variation, whereas waviness and front to back uniformity on plate is usually caused by chemistry and/or processor drive system (check rollers pressure etc.). Hope it helps.

[jrrowellprinting]

We replaced the chemistry before we heard back from a tech on this. Replacing the chemistry did not help the problem. The 50% are coming out at 50% so we don't think it is the setter, although what the heck do I know?!. We are currently cleaning all the pump's and hoses since the tech thought it might be that the chemistry is not circulating properly due to a clog in a drain hose. We are crossing our fingers and waiting to see what comes of cleaning the hoses (my co-worker is cursing up a storm while having to take apart his least favorite machine in this place!) Thanks for your replies... I will let you know what happens.

[jrrowellprinting]

OK so the verdict with the hoses is that the first two sets of plates came out looking beautiful, but the third set has a spot where the image looks cloudy (lighter than it should), or with the same inconsistent dark and light areas that I discussed in the first post of this discussion. My question is this... if it is that the mirrors or optics need to be cleaned in the setter, would the cloudy areas be in the same spots on every plate that I run through it or would the cloudy areas be in different spots on every plate? if I can run some plates through and visibly see that the bands of light areas vs. dark areas are in the same position every time then wouldn't it be a setter issue since chemicals in the processor are liquid and can not be expected to mix incorrectly in the same spot every time? I am really just trying to figure out which is my issue... the processor or prosetter. I guess I won't know until I send a plate from my prosetter to somewhere else to be processed, but the only one in town that has a processor similar is our competition and we don't get along! I hope this question makes sense...

[maxon]

JR,
Makes perfectly good sense... You referred to the affected plate area as cloudy, do you mean out of focus ? You described the problem better in your last post, all points to exposure problem not processing. I don't have any experience with prosetters, but if I suspect vacuum problems / air pockets in any internal drum machine I would bypass the cover interlocks, feed a plate in (any plate, even a processed one) wait until vacuum is on then put a flashlight in to visually check the plate to drum conformity, one can easily see if the plate has been fed in the correct place and perfectly vacuumed.

As a side note, you can cut an exposed plate to obtain a square then rotate 90 degrees and feed into the processor to completely rule out the proc. as a possible cause, but I bet it's something to do with the ctp.
Large diffuse cloudy round areas are one thing and may indicate vacuum problems, banding across the plate is something different and usually points to traverse/carriage movement during scanning. Can you attach a picture of an affected plate here ?

[maxon]

Besides, thread is called plates not holding ink properly which typically indicates too low laser energy on plate I've seen this with both Kodak and LP-NV, Fuji more often when underexposed, and lower energy can be due to poor focus caused by low vacuum, stuck solenoids, foreign matter or dust inside drum, bent plates a.s.o. ... love flatbeds.

Of course all of the above applies to photopolymer plates but worth considering nevertheless.

[Ozkan Hangisi]

Hello Jr.

Hope you have already solved your poblem. I will suggest some points to check anyway. Clean the rotating mirror and optic head lens. Any dirt on these parts creates extra expose some areas and plate looks lighter exposed. Most important roller in silver processor is exit roller of developer tank. If roller pressure is not enough, one side or rear edge of plate will still have thin layer of developer till the washing unit. And this area looks lighter because of extra dev. time. Order new developer rollers. Good Luck

Ozkan

[Hessel]

We have the same problem, but we are using Polaris XTV and LP82. But our plate and print looks cloudy to. We have the problem for 1,5 years now.
But take a look at your plate out of the box , you can see a cloudy patern already.
Do the plates also blind after a longer run?