Electrochemical Impedance Analysis of the Wear of Planographic Plates^☆

Chemically roughened and anodized Al sheets containing an oil-loving photosensitive organic compound provide the image carrying component for the high-speed planographic lithography used in the newspaper publishing industry. New concepts for printing press design require an understanding of the mechanism of wear and degradation of these surfaces. Electrochemical impedance spectroscopy senses chemically and tribologically produced changes on the surface of a planographic plate. A concept for an electrochemical impedance wear monitoring device has been tested. Wear and degradation processes tend to increase the capacitance of the anodized Al surface of the plate. Measurement of the plate capacitance during an actual press run provides some insight into the wear process.