Ink/Plate Interactions in Waterless Lithography

With the elimination of fountain solution used in conventional lithography, the ink/plate interactions become important in the operation of waterless lithography. An important parameter akin to the ink/water balance in conventional lithography is Critical Toning Index [CTI]. It is the temperature above which the non-image area starts to accept ink or tone. Rheological and surface chemical studies on several inks and plates have enabled us to identify the relevant physico-chemical properties of the plates and inks which have an influence on CTI. An empirical equation was then derived which allows us to predict CTI, based on these properties.