ASTM D2240 measures the hardness of rubbers using twelve types of rubber hardness measurement devices known as durometers.
Durometers can be used to measure the indentation hardness of thermoplastic elastomers, vulcanized (thermoset) rubber, elastomeric materials, cellular materials, gel-like materials, and some plastics. This test method does not apply to testing coated fabrics. ASTM D2240 measures hardness based on either initial indentation or indentation after a specified period of time, or both.