TRANSFER AND SETTING OF WATER-BASED INK .2. PH, WATER ABSORBENCY AND UNCOATED PAPER STRUCTURE

A series of kraft handsheets of controlled pH and water absorbency was prepared and printed on a single-sheet flexographic proof press, with a water-based ink. Ink transfer increased with increasing water absor bency. Ink penetration also increased with water absorbency, although the effect is small in the commercial range of ink levels. There is a slight increase in transfer of this alkaline ink to more acidic papers , but there is no apparent influence of pH on ink setting. A series of newsprint samples was also printed. Within related wood species, prin t density on newsprint increases with fines content, while set-off dec reases with increasing surface fines. The correlation between print-th rough and opacity is much better than was found with oil-based inks on the same newsprints, due to the absence of oil penetration effects.