FORMATION AND CONSOLIDATION OF A COATING LAYER AND THE EFFECT ON OFFSET-PRINT MOTTLE

The literature on the formation and consolidation of a coating layer i s reviewed, with emphasis on the occurrence of mottle in offset printi ng of coated paper. The review first defines and examines the press-re lated causes of mottle. The stain tests used to predict offset mottle are described along with their limitations. The main portion of the re view is devoted to paper-related causes of mottle. The interaction bet ween the coating color and the base paper during coating formation and consolidation is a focal point of discussion. Special attention is pa id to factors influencing the distributions in mass, porosity, and bin der content of the coating layer and their relation to mottle in the o ffset print. The role of calendering is also examined.