Testing Methods

When the development of leather substitutes was started the aim was to sub-stitute leather in shoe production. In the USA, Japan and Western Germany the water vapor permeability was characterized by measurements according to DIN 53 332, respectively, IUP 15 or similar methods [1]. According to IUP 15 a circular testing piece is placed into a small vessel containing a desiccant like silica gel. The testing piece is conditioned at 23°C and 60% relative humidity overnight. The next morning the silica gel is removed and replaced by fresh silica gel. After weighing the vessel, the absorbency of water vapor from the standarzied surrounding air is measured by weighing it after 8 h, The weight gain is divided by 8 and divided by the area of the testing vessel which has a constant size. The resulting value is a water vapor permeability measured as an absorption of water vapor at the silica gel in (mg/h · cm2). In Japanese publications the result was transformed into mg/24 h · m2. However, the results were comparable with the IUP 15 method.