Modeling Studies of Ink, Plate, and Fountain Interactions by Contact Angle Measurements (3).

The concept of the ink spreading force measured with an ink-fountain-plate three phase contact angle setup is applied to study positive litho plates. In model studies, it is found that the non-image area of positive plates strongly interacts with soy oil. Measuring the contact angles of soy oil surrounded water and fountain droplets thus can be a useful technique to differentiate positive plates and related developers. In contrast, interaction between positive plate non-image area and Magie oil are insignificant, so are the interactions between plate image area and either oil.