Coating pore structure and offset printed gloss

Both gloss and ink absorbency of a paper surface influence printed gloss and affect the flatness of an ink film. With certain changes in coating pore size, absorbency differences outweigh underlying paper gloss in the effect on printed gloss. A series of discrete, isotropic, monodisperse, calcium carbonate pigments produced coatings with well defined and different pore size distributions. In laboratory coated papers, paper gloss increased and offset printed gloss decreased with decreasing particle size. Change in gloss due to printing showed high negative correlation with the ink setting rate. Both printed gloss and ink setting rate correlated strongly with coating pore size distribution. Larger total pore volume and smaller average pore diameter caused faster ink setting and lower printed gloss. Application: Coating absorbency profoundly influences printed gloss.