Dermal Surface of Sheep-skin

Abstract

IN the dermal surface of sheep-skin a natural feature has been noticed, which is the origin of a defect in the appearance of some gloving leathers. During manufacture of leather the epidermis is removed, the exposed surface becoming the ‘grain’ of the leather, and small dark spots, scattered several mm. apart, occur on the grain surface of some leathers. A spot is illustrated in Fig. 1 (top), which shows the surface of a leather made from an Abyssinian sheep-skin. The rows of dark regions represent the mouths of hair follicles and an offending spot lies between two such rows. Microscopical examination of cross-sections showed that the spot was not due to diseased or scar tissue, but that the surface connective tissue fibres had been damaged and were, in the leather, stuck together to give a glassy appearance to the spot. The examination of some other leathers of similar type, the origin of which was, however, not precisely known, gave a lead as to the cause of the spots. Fig. 1 (middle) shows a small tongue of tissue rising from the grain surface: the camera is looking along the grain surface so that the tongue is seen in profile. Fig. 1 (bottom) shows the base of a tongue in cross-section: it is fibrous and continuous with the general fibrous tissue of the dermis. The distribution of tongues was similar to that of the spots, and it seems reasonable to conclude that they rub off during processing, leaving the unsightly spots.