Having stripping problems? Just can’t get ink to stick to the copper drums, which causes the printed page to be too light or have no ink at all in the affected area. In some cases pressmen have tried to fix this area by wrapping Ruby-Litho tape in the affected area or have used a copper coating solution to improve the copper drums ability to repel water. It will work but is not a permanent solution to the problem. If the copper is worn off and the steel is showing the best solution is to replace the copper drum with a new or reconditioned one. The recondition copper drums for single-width single plate around press such as Community press unit costs approximately $260 reconditioned and $600 new. The reconditioned copper drums for a single-width two plate around press are approximately $390 and approximately $800 for a reconditioned Metroliner copper drum. Of course you will have to contact your parts supplier for exact pricing.
The copper drum may not need replacing. The copper may appear dull or have the appearance that steel is showing. The copper drum may have a film coating, which is covering the surface of the copper drum and will prevent it from repelling water rapidly. Fig 1 is water droplets on a copper drum that is in good condition. Notice the height of the water droplets. The water droplets will not spread across the surface of the drum easily, which creates a dry surface more or less, allowing the ink to adhere to the surface. Fig 2 on the other hand is a copper drum that has a film coating that is allowing the water droplets to spread across the surface of the copper. The water droplets will eventually form a continuous film of water across the surface where the film coating is, causing this area of the copper drum to lose its ability to carry ink.
The film on the copper drum is a hardened deposit of ink, paper and other chemicals that come in contact with it. The film can be removed with a copper or brass polishing solution that can be purchased at your local home improvement store. This takes a lot of elbow grease but will provide excellent results. The easiest way to apply the solution is to remove the ink rollers that contact the copper drum allowing better access to the affected area. Be sure to remove all of the polishing solution with water after you have finished the process.
If time is available I like to remove the copper drum, then install the drum in a lath and use green scratchy pad to remove the film deposit. Once the film has been removed I use steel wool to finish smoothing the surface of the copper drum. The copper drum will look and work as well as brand new. The scratchy pad can be used right on the press as well; however I don’t recommend that it be done while the press is running, for safety reasons of course. In order to remove the film with the scratchy pad, first remove the two ink rollers that come in contact with it. Then with the scratchy pad and elbow grease remove whatever film you can get to and then rotate the press to a new position and continue the process. This is just as effective as removing the drum as far as removing the film but the appearance of the drum will not be as smooth. The process of removing the film from the surface of the ink drum with a scratchy pad can also be used on other types of ink drums as well since they will develop the same condition.
Frank Bourlon has more than 30 years experience in the newspaper industry. He is the Associate Director for Newspaper Production & Research Center. He can be reached @ 405-524-7774.