Temperature and moisture effects on wetting of calcite surfaces by offset ink constituents

Offset printability is influenced by interactions between ink constituents: linseed oil, mineral oil and water (fountain solution), with the mineral surfaces of paper coatings. To exclude complications of the porous structure effects, the influence of temperature and moisture on wetting by offset ink model liquids were studied on cleaved optical calcite surfaces with and without sodium polyacrylate dispersant. Contact angle measurement was chosen as the method of analysis. The results show that a moderate temperature increase from 25 degrees C to 60 degrees C, which might occur in the process, does not affect the wetting of these surfaces by mineral oil. Water and linseed oil are affected by the transport of moisture at the surfaces as an indirect consequence of temperature increase. The linseed oil behavior was found to be sensitive to polarity changes of the surfaces.