Effects of Ink Input Volume Changes on Printed Quality During Keyless Lithography

A conventional heatset offset web press was made ready for printing a group of process color graphic arts images by setting keys until the predetermined printed target single-color densities across the web were achieved. While continuing at constant speed and dampener input, the overall rate of ink output was increased or decreased by significant amounts both individually and for combinations of inks by increasing the ink ductor frequency. The intent was to simulate the effects of inadvertent differences in ink delivery during keyless inking due to doctoring errors or because of metering roller wear. The only significant apparent quality variation was hue of the prints when compared to a standard. Data on optical densities, dot gains, will be presented.