Sucker feet marks on poly plates...

P

pressmanken

Active member
They started showing up about 2000 impressions in. The plate became sensitized and began printing where the sucker feet hit the envelope. I'm in a hurry, so I may leave out something you need to know, but the press is a 3302M and I'm running #10 windows in 185/300. The fountain solution is Anchor, with an alcohol substitute. 6oz, 3oz/per gallon, respectively.
 
Sucker feet

Sucker feet

That seems way to early in the run for the plate to become sensitized. Should get over 50M impressions on a poly plate.

Two thoughts:
1) Are you adjusting impression for the variably thick envelope?
2) Check you plate chems. The developer or fix could be bad.

Angelo
 
Is it showing up on the first unit more than the second? If so it usually the paper fibers from the envelopes. Check your blankets if there is paper dust on the blanket it is wrecking your plates. The only way to avoid this is wash your blanket and make sure the all the dust is off your blankets. you can revive your plate by using black plate etch. If there is no paper dust, I have seen some after market sucker feet cause this problem you can wipe them down with some blanket wash and this should help.
 
Sucker feet marks...

Sucker feet marks...

Printdog said:
Is it showing up on the first unit more than the second? If so it usually the paper fibers from the envelopes. Check your blankets if there is paper dust on the blanket it is wrecking your plates. The only way to avoid this is wash your blanket and make sure the all the dust is off your blankets. you can revive your plate by using black plate etch. If there is no paper dust, I have seen some after market sucker feet cause this problem you can wipe them down with some blanket wash and this should help.
Click to expand...

Printdog, I believe that is what I'm dealing with. It does show up first on the #1 head, and there is paper dust on the blanket adjacent to the affected areas on the plate. I was also running bond envelopes, and already suspected the paper fibers. Etch works at first, then I have to make a new plate(if on a long run). Our feet come from Mac. I will try wiping them as you suggested. The other thing I noticed after I posted, was that the water tank was low, and the solution was aerating. I am thinking that had something do with it, as well. Thanks, all for the responses.
 
Pressmanken, If you watch the envelopes when they transfer to the feed rollers the sucker feet drag on the envelope causing abraisions which tranfers to your blanket in turn wrecking your plate.
Sometimes you can run the envelopes without using sucker feet. This will help. good luck.
 
Back in the olden days we used to put a single layer of cheese cloth over the suckers (with rubber bands). It would keep the suckers from disturbing the fibers in the paper. It also worked when you were going through the press more then once, to keep any powder buildup marking from the suckers.
Haven't had to do it in a decade or so.
Lenny R.
 
Sucker feet marks...

Sucker feet marks...

I ran some carbonless the other day, without feet, and it still marked. Not only where the suckers pick up the sheet, but also about 10 inches down on the non-op side of the sheet, as well. Weird?:confused:
 
Did it on some 11*17 bond yesterday, also. Started marking about 3000 sheets into the job. This is with no sucker feet. Solution too hot?
 
If you are not running any metal plates you really should be using a fountain solution that is glycerin based that is designed for poly plates. The fountain is usually pink and is mixed about 15 oz per gallon and maybe about 1 oz of alcohol sub to that gallon. Most anchor solutions are designed to give proper alkalinity by using acids to have a desired effect on metal plates. In your case glycerin is used as the wetting agent to keep non image areas clean. If you are using an anchor product that is designed for metal the max concentrate you should be using would be under 4 oz and more likely then not 3 oz per gallon. What is the number of the anchor fountain you are using?
 
Sucker feet marks...

Sucker feet marks...

I reduced the fountain solution mix to 3 oz/gal. It seems to run a lot longer before they begin to appear. Ran almost 10k bond #10s this morning before I could see the marks begin to appear.
 
Sucker feet marks...

Sucker feet marks...

VladCanada said:
Hmm
Is it possible to add some ground wire at sucktion cups assy to remove the static charge?
Click to expand...

Don't think static electricity is my problem. The press has a discharge bar on the feeder, in any case. So far, the weaker fountain solution mix is working.
 
Still having this problem. Happens on some jobs, but not on others. Currently running Strathmore 88 cover bristol. New plate processor chems and cleaned and refilled water boy. Same Anchor chems listed earlier, at; 3 oz/gallon and 4 oz/gallon alc. sub. It has been suggested I try adding various additives. Antacids, ground up into powder, coca-cola (serious). Going to try adding more substitute, and maybe try changing solution altogether, if I can find any here. Whatever it is, it started within 500 sheets. I have 7500+ to run. Ugh.
 
pressmanken said:
Still having this problem. Happens on some jobs, but not on others. Currently running Strathmore 88 cover bristol. New plate processor chems and cleaned and refilled water boy. Same Anchor chems listed earlier, at; 3 oz/gallon and 4 oz/gallon alc. sub. It has been suggested I try adding various additives. Antacids, ground up into powder, coca-cola (serious). Going to try adding more substitute, and maybe try changing solution altogether, if I can find any here. Whatever it is, it started within 500 sheets. I have 7500+ to run. Ugh.
Click to expand...

Are you serious??? is this just a new problem with the paper you are trying to run? If it is happening with all kinds of paper plus paper you have run for a long time with no issues change your chemistry!! clean out the plate maker with a fresh batch. change to a different fountain solution & an ink recommended for that fount.

Particular types of spray powder can cause issues on the second pass but you are having issue with first pass.

The notion of glycerin needed to be in a poly plate fount is crap!! It's a good additive if you want reduced drying times though. An old school thought & remedy that has been overcome by better advanced founts.
 
I would suggest running your ink and water balance a little differently. Polyester plates love water and as a result you should probably be running ink and water about 5% or so higher than you would with metal. Also a fountain solution with glycerin will help but that may be at the risk of slow drying. The water on the plate acts like a lubricant and will resist the abrasion from the paper particles the suckers deposit on the blanket via the stock. Pressman learn to run the balance with the least water possible but with poly that can add to these problems. Is the lead edge of your plates building up with ink too? Lead edge creep. Kinda the same issue, the forms climb on to the lead edge and if the plates aren't wet enough the ink builds up where the forms hit and eventually works it's way down the plate. You might try not using an alcohol replacement as they are there to reduce surface tension so you can run a thinner film of water, great for metal not always best for poly. Mitsubishi makes an additive called SLM-OA2 which is Amorphous silica and ethylene glycol. This additive is used so people can run metal or poly without changing fountain solution. Bottom line is this additive adds the lubricant the poly plates need. Amorphous silica is soapy or slimy which is also a form of lubricant. These things should help but if there is enough pulp or abrasive product getting to the blanket the poly plates will break down prematurely. Lubricants extra ink and water should delay the symptoms.
 
Rubbish

Rubbish

Hello MSLDoug,


Again rubbish, Polyester Plates do not love water, they need excessive amount of F.S.

for them to work successfully in Lithographic Printing


Regards, Alois
 
Alois

I beg to differ. I have spent my career making polyester work and the most successful operators keep these plates wet at start up and through the run. With polyester plates you are running the photographic emulsion directly on the blanket. it is a porous surface that needs more water to operate successfully than metal. The issue in this problem is the crud on the blanket wearing the poly plate which is softer and not as durable as metal. I am simply trying to suggest things that might help this person solve their problem. Extra water, fountain solution whatever may help. I have taught people running poly for years to turn up the water 5-10% compared to metal, adjust the ink accordingly and hold your balance there. I stand behind my statement that the polyester surface works better with more water, fountain solution whatever you want to call it, than a smooth high grade aluminum surface, it is simple physics.
 
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