Ghosting in screen....

[kdw75]

On a 4-color GTO with a central water system I have had problems with the cyan unit. I will try to describe what happens. We have a sheet that has a screen around 30% and in front of that there is some bold type reversed out of it. After several thousand sheets we will see the reversed type show up in the screen by causing the screen to plug in the shape of the letters. Then once this happens the only way to fix it is to use a plate desensitizer. The fix usually lasts a few thousand more sheets. The press has Crestline dampeners.

 

[white rabbit]

On a 4-color GTO with a central water system I have had problems with the cyan unit. I will try to describe what happens. We have a sheet that has a screen around 30% and in front of that there is some bold type reversed out of it. After several thousand sheets we will see the reversed type show up in the screen by causing the screen to plug in the shape of the letters. Then once this happens the only way to fix it is to use a plate desensitizer. The fix usually lasts a few thousand more sheets. The press has Crestline dampeners.

I have never run Crestlines, but what does the image on the blanket look like ? Is there a buildup of paper fibers, or anything ? Your form rollers may be picking up the stuff that has transfered from the blanket to the plate.

just a thought,

B

 

[kdw75]

The blanket looks pretty good. No noticeable buildup in the area.

 

[RGPW17100]

How old are the crestline rollers? Typically you are looking at a year before replacing them. Verify all your ink forms and pressures to the oscillators are good. Cyan is usually one of the first units to show roller problems. I would try to first use a calcium rinse like roller relief or deluxe roller cleaner. If you have a spare set of water rollers or a unit that has been replaced to move those rollers to the cyan unit and see if the problem persists.

 

[Ajax]

I've seen this happen on a different press before. Turned out a bushing went bad and the rollers stopped oscilating. Make sure your oscillating rollers are well, fully oscillating.