An Investigation of Coated Paper Wet Pick Using Scanning Electron Micropacy and the IGT Printability Tester

Lithographic lore implies that when wet picking (milking) of coated paper occurs, the coating accumulates on the blanket and may move against the flow onto the plate and beyond. Such an effect would make this problem easy to detect if it could be relied upon. The appearance of wet pick on a print can be similar to wet repellency and is easy to misinterpret if the print is the only piece of evidence. A technique for analysis of the surface of a print by scanning electron microscopy was developed that can answer the question was it pick or repellency? A foundation was laid for development of a reliable laboratory print test to predict coated paper's interaction with fountain solution during lithographic printing. By examining the same paper in cross section, possible mechanisms by which wet pick may occur have been postulated. A technique for analysis of the surface of a print by scanning electron microscopy was developed that can answer the question was it pick or repellency? A foundation was laid for development of a reliable laboratory print test to predict coated paper's interaction with fountain solution during lithographic printing. By examining the same paper in cross section, possible mechanisms by which wet pick may occur have been postulated.