Many advances have been made in developing rapid ink drying systems, but most printers will have to contend with spray powder to prevent setoff well into the foreseeable future.
Powder tends to accumulate on presses, overhead light fixtures, ceiling rafters, and surrounding pressroom areas. Press operators often overlook the fact that such buildup interferes with press performance and print quality. Powder that builds up in grippers, press motor bearings and gears, and in the delivery system can affect press performance. Such accumulation causes mechanical malfunctions that hinder the press operator’s ability to control print quality. Print quality is affected when spray powder above and around the press falls into the press units and causes plate wear, hickeys, and other undesirable spots. Causes of hickeys are difficult to locate during a pressrun and are time-consuming to remove.
Excessive powder accumulation on and around the press results from inadequate housekeeping maintenance and from the tendency of some press operators to run excessive spray powder. If excessive amounts of spray powder are applied to overcome ink setoff in the delivery pile, the press operator may be overlooking the real cause of the problem.
Recommendations for reducing the amount of spray powder used in the pressroom:
- Keep spray powder system clean and moisture-free
- Carefully observe how much powder is applied by using a sheet of black paper
- Eliminate static electricity
- Check retention of spray powder on the paper with low-angle light source
- Choose the proper grade of powder for the paper being printed
- Select the compatible ink for the paper to be printed
- Exhaust or trap excess airborne spray powder
- Utilize infrared radiation systems to help to set the ink
- Apply water-based coatings
- Work with the customer to create designs that reduce problems