Optimizing Lithographic Performance - A Physical-Chemical Approach

It is postulated that in order to obtain the best startup performance on a lithographic press, the thermodynamic driving force should have a positive value. An equation, which takes into account the surface energies of the litho plate, ink, and fountain solution, and their polar and dispersion components to calculate this driving force, is derived. In order to correlate with press performance, especially at higher speeds, a time scale for the dynamic measurement of surface energy is suggested, and the magnitude of some of the times involved in printing is calculated. From rheological measurements on fountain solution/ ink emulsions, it is concluded that thermodynamic stability of such emulsions is desirable for optimum press performance.