Plate/Press issue - After washing up/gumming plates will sometimes leave a track mark

[dgraves8rd]

Plate/Press issue - After washing up/gumming plates will sometimes leave a track mark that will not come off plate.
Press: Komori 540
Plates: Agfa Azura
We have been experiencing this issue and have not been able to figure it out. This doesn't happen all the time and not even on the same cylinder.
Pictures are attached.

 

[Al Ferrari]

What colors make up those marks?

How are you gumming the plates? The marks may be appearing only from units that were gummed less generously than the others. My thought is that the marks appear when the gumming fails to cover up the real cause.

The spacing of the marks appears regular and not random. Are they related to roller defects, or locations on rollers corresponding to some type of build up on the rollers?

How does length of run before the wash up/re-gumming relate to if the marks do/do not occur? The cause of the marks may be at work on all run lengths, but not showing up on the shorter runs.

Examine ALL form rollers for debris buildup at the location of the marks. Be sure to examine hidden ink form rollers.

Report back.

Al

 

[dgraves8rd]

The plates are not being gummed except when being made . The pressroom has changed all rollers touching the plates and that didn’t help. They changed the chrome roller in the water unit and that didn’t help. The color of the marks are black and magenta.

 

[Al Ferrari]

If the color of the marks is black and magenta, it's fair to assume that the cause of the problem resides in those two units. But why do you suppose the marks appear to be related to the travel direction of the sheet, and that those two sources are aligned with each other?

It may be very instructive in the long term to find the cause of this localized problem. But it may be simpler in the short term to simply gum the plates between runs.

Al

 

[dgraves8rd]

Seems like we have tried to isolate the known areas, but still have the issue. We were hoping someone would see the pics and maybe know a solution.

 

[Alois Senefelder]

Sensitized Plate Marks !

Sensitized Plate Marks !

Hello Dgraves

1) Blanket Wash being picked up from plate lead edge. 2) A poorly set roller in the roller train.

3) POOR wash up procedure 4) POOR gumming up procedure

5) Leaving Blanket Wash splashes on the plate, result: Sensitized Marks !

6) Gum the Plates ! - or have the Down Time !!!

Regards, Alois

 

[Kaoticor]

Hi dgraves. Trying to understand exactly what is happening. In your original post you said:

"After washing up/gumming plates will sometimes leave a track mark..."

Later on, you said:
"The plates are not being gummed except when being made."

I am probably missing something but would you be able to clarify so perhaps we might be able to give you more feedback? Thanks,
K

 

[tomcatinc]

Agfa Azura plates are negative working plates. They are "developed" in gumming soultion. Actually it is not developing (there is no chemical reactio) - it is washing in gumming solution. There is no developer. Gumming is done in turn with washing - washing/gumming unit has only one wet spot: from entrance to drying unit. There is no washing with water.
If you lack the proper gum, you can wash the plate with small amount of mild dish detergent (without any glycerine or similar additives) and immediately wash it with plenty of water then gum it with standard gum.
Simple advice: wash in washing/gumming unit unimaged plate, wash it with water and put it to press.
This print marks are too regular to be plate related. As I can see, the marks period is smaller then plate size and is probaly of water or colouring rollers.

Maybe you can check this: if the plate is not put well in gripper or the plate is not bent in straight line, it can hit a roller and pick up some ink. Ink spread rollers would spread that while turning. So, marks are small and of intense colour on the begginig of paper and larger but lighter going towards end of paper. The guy that had this problem had dirt under plate gripper and it was rising plate by 0.5mm - well enough for plate

 

[spharris]

when this happens again check to see if your water meter and or other water rollers have a fair amount of ink on them like in the black or red units. this could be causing your sensetivity and you have to scrub plate and re gum to get it to go away .also clean water meter with mrc etc etc hope this helps sure sounds familiar

 

[Lennyr]

gumming issue

gumming issue

The plates are not being gummed except when being made . The pressroom has changed all rollers touching the plates and that didn’t help. They changed the chrome roller in the water unit and that didn’t help. The color of the marks are black and magenta.

I had the same problem and it turned out the the drying unit on the plate processor wasn't working well enough to dry the plates properly and the marks were coming from the feed rollers.
Lenny R.

 

[Elewis]

looks like when you are hanging the plate there is some ink build-up on the roller that holds the plate up.

 

[dgraves8rd]

I was incorrect in my earlier post (I'm the prepress manager), plates are imaged and gummed. Once on the press, the marks appear after running.

 

[dgraves8rd]

I don't think it is a plate problem....this only happens on one press. The other presses do not get the marks.

 

[Kaoticor]

dgraves,

If the plate starts up fine but then gradually accumulates those marks, it definitely looks like contaminate in your water system. Changing the chrome roller or the metering roller will not help if this is the actual cause, we went through the exact same problem a few years ago. Contaminate (like hard particles of debris, could be various things) sticks on to your water rollers, especially your form roller. It looks like there are several things, but it could be actually only one piece of debris, and the oscillation will time it to make it looks like "tracks". I would check and make sure your fountain solution is clean, your filters and clean and/or changed, and you are washing your water system very good. Just one possibility.

K