Coating of Paper Sheet with Insoluble Gelatin

Abstract

Treatment of paper with internal sizing agents, not only reduces the penetration of liquids, but also affects the permeability. The mechanism by which sizing brings about resistance to penetration by liquids is explained by the contact-angle theory. Also the precipitation of the rosin size on the fiber forms a water-repellent film upon drying. On the other hand, surface coating of paper sheets with gelatin-hexamine mixture, in different concentrations, results in an improvement in the permeability compared to the uncoated sheets. This could be due to the penetration of the gelatin through the pores of the paper sheet and precipitates as an insoluble film on the fiber, due to cross-linking formed through formaldehyde, which is liberated as a result of hexamine degradation.