Abstract

Specimens of two full chrome upper leathers without any finish were moistened and pressed between heated flat plates to temperatures similar to those used in hot lasting and pre-forming processes in shoe factories, with the object of finding whether the leathers were made stiffer, and whether there were any signs of damage (or incipient damage) to the leather. The pressing caused, in some circum3tances, substantial decreases of thickness, and the leather, considered simply as a sheet of material without regard to its thickness, was sometimes stiffer and in other circum stances less stiff than before pressing. The same was true even if the de creases of thickness were taken into account, and the intrinsic stiffness (measured by the bending modulus) was measured. At the highest tempera tures tried, with specimens wetted thoroughly and pressed for 10 minutes to relatively high pressure, the stiffness was increased several-fold, but this is still comparable with location to location differences on a single side, and the stiffness changes are regarded as due to changes of fibre-to-fibre adhesion and to compaction of the leather rather than to fibre damage. Lastometer tests on the hot pressed specimens also reveal no signs of damage, and it appears that moistened full chrome leathers of high shrink age temperature can be heated by contact with metal plates at temperatures up to 125°c for 10 minutes without any appreciable damage. It should not be inferred that no damage will occur to leathers of other tannages or to leather finishes.