Lightweight Printing Papers of High Opacity.

A new class of printing papers, characterized by ream weights of 17-35 pounds per 25 x 38 x 500 sheets, TAPPI opacities of 80+, and G. E. Brightness of 90#, have been made possible by technical advances in lightweight paper production. In designing these papers, it was found that the high opacity levels desired could be achieved by (1) using a standard degree of pigment loading with a high proportion of pigments such as titanium dioxide with high opacifying capabilities, or (2) by using fillers of average opacifying character in unusually large amounts. The advantages and disadvantages of these alternatives are discussed. The problems encountered in keeping curl, static buildup, ink receptivity, and other printing characteristics at optimum levels are discussed. Technical problems in cutting, folding, staining, and gilding are described. Possible solutions to the problem of providing water resistance for offset printing are discussed in general terms.