Plate cleaners come in acid and alkaline varieties. They typically contain strong detergents and emulsifiers and the alkaline (high pH) washes may contain sodium and/or potassium metasilicates. The meta-silicates will stay in solution as long as the pH of the cleaner stays above 10. These metasilicates are also found in CTP plate developers. Typically it is recommended to use acid plate cleaners on CTP plates, however, an alkaline cleaner can be used on post-baked CTP plates.
It is extremely important to avoid contaminating the dampening solution with the Plate Cleaner for several reasons. Contamination of the fountain solution with alkaline plate cleaner will cause excessive foaming. Due to the high alkalinity it will use up the buffer capacity of the fountain solution. As the fountain solution drops the pH of the plate cleaner below 10 the meta-silicates will come out of solution or precipitate creating gels and will cause the fountain solution to get cloudy. This will quickly plug filter media causing premature filter change outs. It takes a small amount of alkaline plate cleaner in the fountain solution to cause a major problem.
Plate cleaners will also cause ceramics rollers to pick up more ink since it destroys the hydrophilicity of the surface. Re-wet the rollers with clean fresh fountain solution to help restore the hydrophilic nature of the roller.
Ideally, use as little plate cleaner as possible on the plate only. Do NOT put the plate cleaner in the fountain solution or spray the cleaner on the plates in copious amounts to where it drips off the plate and into the dampening system.