HEATSET OFFSET DRYING ON LABORATORY AND PRODUCTION SCALES

This article examines the results of both laboratory and industrial scale test printings and heatset dryings and the connections between them. The purpose of these tests was to acquire new information about the drying of inks on different papers in order to optimise heatset drying. The papers and inks used in this study were selected broadly to cover the papers and inks generally used in heatset offset printing. The drying result was analysed in terms of solvent retention, roughness, rub-off, density and gloss measurements and a subjective pair comparison. New measurement methods were devised. The results of the measurements were used to assess the significance of both paper and ink in heatset drying in relation to drying temperature. The solvent retention measurements showed that the drying of print depends very much on the choice of the paper-ink combination. According to the measurements, each paper is characterised by its own specific temperature-dependent drying curves in terms of solvent retention, gloss, rub-off and roughening. With new kinds of printing inks the print dries with less energy and the gloss of the print is better.