Post-Printing Changes in Printed Ink-Layers and Their Effect on Smearing

The concentration of the ink components in a printed ink layer changes with time after printing. This has been studied on newsprint. The penetration of the ink into the paper structure, during which a partial separation of the ink components occurs, has also been studied. The influence of these two phenomena, the concentration change and the penetration, on the set-off resistance and the rub-off resistance of the printed ink layer has been studied. The carbon black particles of the ink are stranded on the fiber surfaces and form a., a superficial pigment layer and b., a pigment layer located deeper in the paper structure. The first mentioned layer is discussed with reference to its importance for some properties of the print. The redistribution of the ink vehicle in the paper is an important factor affecting print through. The dependence of the print through value as a consequence of the changes in the printed ink layer and of the 0redistribution of the vehicle phase has been studied.