• When tying drawstring covers always use a square knot. (What's a square knot? It would be very difficult to explain in words here...perhaps you can check with a former Boy Scout!)
   
• Hot water is necessary to activate the shrinkage properties of most synthetic dampening covers. If the water is too hot, however, the cover could be damaged. The best guide to temperature selection is to use a water setting that is as hot as you (i.e. your hand) can comfortably withstand.

When to Change Dampening Covers

Every week? Every Month? Every year?
It depends on a number of factors, but there
are some telltale signs that indicate the need.

Regardless of the brand used, a dampening cover which has exceeded its useful life is an invitation to press operator frustration and increased operating costs. It is always cheaper to change the cover rather than to fight the myriad of time wasting problems that an exhausted cover produces.

The most common indicator of a cover that is ready for changing is reduced dampening performance in the form of balance and control problems.

A primary cause is ink buildup on the cover surface. All dampening products will attract a thin film of ink from the printing plate. This ink works its way back into the dampening system depositing itself on the form roller cover, and, to a lesser extent, the ductor roller cover. Covers should be cleaned on a frequent basis to eliminate the ink buildup before it dries. Hardened ink deposits clog the dampening cover fibers making the capillary action necessary for fountain solution transfer difficult to impossible.

Another indicator of exhausted cover life is outer fiber or pile loss. The abrasive contact of the cover surface to the printing plate results in a slow but steady loss of the water receptive surface. This loss can be very subtle and is, for the most part, unnoticeable. It is usually more severe at the ends of the cover which ride on the edges of the plate.

How often you change covers will depend on run lengths, overall press usage, ink colors, maintenance procedures, and operator skill. The best advice is to change the cover at the first sign of performance deterioration. Remember, the cost of a new cover will be far less than the downtime an exhausted cover will cause.