The Gloss of Offset Ink and Its Relationship to the Gloss and Absorptivity of Paper.

While inks for high gloss must have certain special properties, ink gloss is also often thought of as being closely related to the ability of paper to hold the ink on its surface. Research at the Lithographic Technical Foundation has shown that, in general, poor correlation exists between the gloss of offset ink and the ink absorptivity of paper. However, better correlation was found between ink gloss and the gloss of the paper being printed. An empirically derived equation stating that ink gloss is directly proportional to paper gloss and inversely proportional to the ink absorptivity of paper is presented. The study included coated papers and boards printed with gloss and process inks. The effect on gloss of overprinting dry ink films was studied. It was found that the equation expressing gloss of ink on paper held for overprinting provided the overprinted ink is considered as paper. The influence of ink film thickness on gloss was studied and the effect of wet trapping on a two-color press is discussed.