Abstract

The work described is the first part of a systematic study of the dry heat setting and moist heat setting processes used in the lasting of shoe upper leathers. It took the form of experiments in which squares of a single batch of commercially processed full chrome upper leather, 16.5 cm side, were stretched in the two-dimensional apparatus of Chinn and Ward by amounts which could be independently varied, in the two perpendicular directions. The leather was subjected to dry heat setting or the action of moist air (“steam setting”) as a prelude to the study of moist heat setting, in which these two component processes are combined. There was a significant effect of the magnitude of the area strain on the percentage set (i) in the absence of heat setting (ii) with steam heat setting and (iii) with dry heat setting. Cooling the samples after setting, using an air blast, somewhat reduced the magnitude of the set. A factorial experiment for steam setting revealed significant effects of steam temperature, flow rate and duration of application. A similar factorial experiment for dry heat setting gave significant effects for temperature of air, air flow rate and duration of exposure to the airflow. The latter results were complicated a little by the occurrence of some significant interactions. The decay in stress at constant strain during the setting processes gives a useful index of the longterm plastic set. Dry heat setting proved more effective in general than steam setting in giving high sets.