Is there more to the average plate cleaner than meets the eye? Is there one plate cleaner that can act as a quick fix and solve press and plate cleaning needs? Why don’t plate cleaners work the same all the time? These are some of the questions that RBP technical service reps hear regularly. The following article will try to address them and help take the mystery out of choosing the proper plate cleaner for the job.
With most specialty chemicals, a good match between product and problem usually leads to greater success. Plate cleaners are no exception, as in most cases; specific plates demand the use of different cleaners.
While some plates can stand up to just about any kind of plate cleaner, surface plates, which comprise a major portion of plates currently used, typically require a specific cleaner. A general rule of thumb is to use acid cleaners with unbaked digital aqueous and unbaked positive plates and alkaline cleaners with solvent and baked positive and digital plates.
Alkaline cleaners are extremely effective at removing background tinting and scumming and do an excellent job of desensitizing the non-image area. Because solvent and baked positive plates can withstand alkaline cleaners, it is a good choice for them. However, using an alkaline cleaner on the photopolymer image area of an aqueous plate or unbaked positive plate can cause a loss of image or blinding.
In all cases, follow plate manufacturers’ recommendations or ask your chemical supplier to perform a capability test to determine the appropriate cleaner to meet your needs.
Many press operators do not fully appreciate or value how a good plate cleaner can reduce downtime, new plate costs and wasted paper, while also improving print quality.
A common occurrence in the pressroom is that an operator will begin to have trouble controlling the ink/water balance, see plugging and the deterioration of print quality. He cleans the plate, but the same problems resurface quickly so a new plate is ordered and installed. In this process there has been lost time, at least 15 minutes for plate replacement, wasted paper and the cost of a new plate. Many shops estimate the cost of a remake at more than $100 per plate, counting time and material.
Many times, in instances such as this, a thorough two or three minute cleaning with a good quality, compatible plate cleaner could have resolved the problem and saved time and money.
Problems can also arise when there is a plate change and compatibility of the new plates and the cleaner is not checked. This can cause press problems, poor print, quality, reduced productivity and a frustrated press operator.
Paper waste is a hot issue today, especially on webs. A good plate cleaner can help insure quick, clean restarts, free from tinting or scumming. It can sometimes take up to 4,000 signatures on a restart before they are useable. A proper cleaning can reduce this to less than 500.
Tips to Remember When Selecting a Plate Cleaner