Shear Strength in Printing Paper: its Importance and Measurement.

The need is well recognized for new concepts in the definitions, mechanisms, and measurements of paper strength. In the present printing and publishing climate, this need has become more important with the increasing dependence upon both production efficiency and quality at progressively higher speeds. Physical or mechanical properties of the paper affect press performance, terminal converting, printed appearance, and customer utility of the printed product. This paper considers the rather obscure subject of shear strength in paper. Paper under combined states of loading, such as tension plus bending, experiences destructive shearing stresses. Such conditions of shear are here considered with regard to paper web draws, printing press nips, and folding conditions. Novel paper testing techniques for measuring the shear strength of paper are described.