The plastimeter is the standard SATRA test method for assessing the setting properties of leather. It is also used to test new synthetic upper materials and check the performance of heat setting machines by using a sample of material of known heat setting properties.
A disc of material to be tested is cemented to a brass ring and then placed in the plastimeter's clamping head. It is then deformed by forcing into it a non-metallic dome. This simulates lasting and is controlled by measuring the height of the formed dome of material with a micrometer. The deformation gives an area increase of around 15%.
While it is in the strained position, the dome plastimeter containing the sample is passed through the heat setting machine. After treatment, the dome is removed and the cap height of the dome, shaped in the material, is measured at various times. From this, the dome area is calculated and the proportion of the area increase retained is the 'plasticity' or 'set' of the material.