A Study of Some Ink-Paper Relationships.

A laboratory method for studying some ink-paper relationships previously described elsewhere has been modified to provide more precise control of experimental variables. The earlier method involved the nip-spreading of ink drops on paper by means of a steel cylinder rolling down a smooth inclined plane with subsequent analysis of the resulting elliptically shaped ink pattern of non-uniform density. In the modification described the ink drops have been replaced by uniform ink films of known thickness and a study has been made to determine the influence of nip pressure, paper-ink contact time, and thickness of the ink film on the division of ink between the paper specimen on the cylinder and the non-absorptive surface on the incline. The percentage of ink taken up by the paper from the film on the incline was found to be a function of the ink film thickness and reached a maximum at a film thickness which depended upon the nature of the paper, the nature of the ink, the nip pressure, and the time of contact between the ink and paper in the nip.