Abstract
The quantitative evaluation method of the antitoning property of inks for waterless planography was investigated. It was found that toning was induced mainly by the plate surface temperature. Thus, the plate surface temperature at which toning occurred under standard printing conditions was employed as a criterion of the antitoning property, and was termed the critical toning index.
The critical toning index is not an absolute value but a relative one, and varies depending on printing conditions such as a solid density on a print, roller pressures of a press, and a printing speed.
Investigations on the relationship between the critical toning index and physical properties of inks revealed that the critical toning index was not necessarily correlated with the tack and the flow but was closely correlated with the viscosity or the plastic viscosity at a high shear rate.
