We're running a Quadstack in coldset mode, mostly Newsprint products both Tabloid and Broadsheet. We have recently started getting lines printing across the front and back pages on Tabloids. They are almost always Cyan/Magenta, very thin (one or two dots wide, but rough edged - see attached picture), but under a loupe they do not have the sharp edged look of physical scratches on the plates. To be sure of this we checked the plate punch and the bender for burrs, the CtP was serviced only 2 weeks ago. It does appear that there is a visible build up of what looks like paper dust on the blankets which comes off with blanketwash/water. We are running No-process plates on our CtP, a mild acid fountain solution at a conductivity of 1500 over water and pH of 5.0. Paper, inks, plates and blankets have not been changed but we did recently change over to a new fountain solution that was supposed to run better with No-Process plates. Has anyone else gone through this problem? If so, what was the final outcome?
Richard Fazakerley - Operations Manager
Pacific Publishing Company - Seattle, WA
If you check the finger bars between the plate and blanket cylinders you could quite possibly find some small strips of velcro on the bars. This over time loosens off and gets all crusty with ink and other material. It then drags on the plates and scratches them. Pull that stuff off and should be good to go. Might want to take them off and clean them up properly but I'm sure that's where you will find your problem.
Change both your lower form rollers. The rollers have a piece of sand or somthing imbeded in the rollers.
We had that problem some time ago. It turned out to be calcified deposits that ended up on the ink rollers, wiping the rollers clean helped. The problem originated from the drain/fill you will see calcified water deposits and if let to build-up will eventually end up in your water trays, the brush would flick the very small deposits to the ink rollers. The fix is cleaning the trays and water fills of those contaminents. The lower the tray the more contaminated they are and I suspect that is why it's usually red or blue if thats what you print first. Hope this helps.
Mike B Park Press
Thanks everyone, all comments made sense. We had already checked the rollers for metal shards (from bad bearings etc), we cleaned the guard over the circumferential adjustment shaft. They were not actually scratches. We did eventually find very fine lines on the blankets that washed off with blanket wash and water. we switched back to our previous mild acid and it seems to have cleared the problem. The consensus now is that we were having piling problems (paper dust, perhaps some of the calcified deposit type stuff too.) When we first changed to the new solution, it seemed to pull a lot of muck out of the water system. We run our water return lines from the bottom of the "cascade cups" into a small aluminim tank with a couple of scotchbrite pads as filters, and then pump it back to the main barrel to be re-used. The filters were definitely more dirty with the new solution, so we ran a "Turbo wash" cycle. I think we may have got it sorted out.
Tim, we dont have velcro on those guards since it acts like an ink magnet. We did however pull all of them and clean them. I'm thinking about putting a strip of the 3M auto paint protector strip (like the "bra" they put on cars). this should remain slick, will remove any chance of metal-to-metal contact and hopefully not melt if cleaned with blanket wash. See my comment below for the end result. Thanks for your input.
Thanks for the suggestion Earl, it wasn't actualy scratching the plates (we thought so at first and checked all the forms). Turned out to be a piling problem.
Thanks Mike, that whole deposit issue is why we added a small tank/filter/pump to the outflows on our Quads.
Mike - We use an R>O> system to start the water at zero and then add fountain solution to about 1200 conductivity we then cool it to 45 degrees with a chiller. makes for a stable water system. We have also converted our water pans to a flow thru system (similar to a Goss) this helps with flow and keeping gak out of the trays. Water comdes in on the operator side and goes out on the gear side.We no longer use the tanks because of the flow thru system and it allow us to clean pans once every 4 months as opposed to every 2 to 3 weeks when I first got to Iowa Falls, Iowa from Gannett.