After printing, applying drying powder to the delivered sheets creates an air gap between them that prevents offsetting--the transfer of ink from the freshly printed sheet to the reverse side of the sheet above it. Blocking (sheets sticking together) also is eliminated. But using too much powder reduces gloss and scuff resistance, impairs finishing processes, and may lead to an unwanted buildup in the press.
Tips for correct use: apply minimal amounts of powder with a grain diameter of at least 0.015 mm and a low proportion of fine dust. In jobs involving multiple passes, use only powder containing starch--mineral-based powder can wear away the printing layer of the printing plate. To avoid lumping, always keep the powder dry by storing it in closed, moisture-proof containers.
Sheetfed Offset Press Operating, 3rd Edition
Lean Printing: Pathway to Success
