High Speed Laboratory Printing Studies With a Newsprint-Newsink Combination.

A high speed laboratory printing study was conducted in order to elucidate the mechanism whereby newsink transfers to newsprint. The FOGRA Printability Tester was employed for the majority of the work; limited experimentation was also carried out on the Vandercook Proof Press. Total transfer, optical density, and showthrough generally increased with increasing printing pressure, packing softness, and cylinder diameter. The printing results decreased with increasing printing speed up to 1000 fpm, but over 1000 fpm, the trends reversed in that higher transfer and print properties were obtained than would be expected from the time-pressure dependencies involved. Of the many transfer parameters derived from the data, only the amount of ink immobilized during the dwell time conformed with the reversal in trends observed with printing speed. The dominant mechanism of high speed transfer is therefore attributed principally to an increase in ink absorption during nip contact due to less compression of the paper pores at the shorter dwell times.