The most common hardness test for elastomers is the Shore hardness test according to DIN ISO 7619-1.
Shore hardness is the resistance of a rubber sample to the penetration of a cone-shaped body of specific dimensions under a defined compressive force. To test the Shore hardness, the penetration depth of a needle with a standardised tip is measured.
Common elastomer compounds for technical moulded parts lie in a hardness range of 20-90 Shore A. The tolerance is +/- 5 Shore A. The usual tolerance is +/- 5 Shore A.
The low values characterise “soft” objects, very hard objects have 80 to 90 Shore A.