Shore hardness A and D

The Shore-hardness is a characteristic value for material properties of Elastomers and plastics. It is specified in the DIN 53505 and DIN EN ISO 868 standards. The Shore-hardness-tester (or „Durometer“ ) consists of a spring-loaded indenter, which elastic indentation is inversely related to the Shore-hardness of the material. The scale is from 0 to 100. A high figure means a high hardness.

The thickness of the part to be tested should be 4 mm minimum (out of experience 6 mm is preferable). It is permitted to stack some thinner parts, but these thinner parts must have close contact.

Shore A hardness applies to soft elastomers. The hardness tester has a blunted Tipp. If values above 90 Shore A are measured, the hardness tester for Shore D should be used.

Shore D hardness is used for harder elastomers or plastic materials. The tester has a pointed Tip. If values below 20 D are read, the Shore A hardness tester should be used.

Please note, that additive coatings, like e.g. wax on the surface promote the penetration of the surface rather than the indentation. This give wrong results. It is advisable to clean the parts with alcohol. After proper drying of the part the test can be done in a standard climate (23°C/50% rel.hum.).