Rubber Shore Hardness Scales

24 Oct 2019 | Posted by Andrew Onions

Elastomeric materials are usually measured with either a Shore A Scale Durometer or an IRHD dead load system. These tests are designed for use with samples approximately 6mm thick, and a surface area sufficient to permit at least 3 test points 5mm apart and 13mm from the edge of the material.

Measuring Shore A – D, 0 and 00

The method for measuring Shore hardness’s is through a spring loaded indentation device, on which values are obtained as a function of the viscoelastic property of the material. The cone indenter extends 2.5mm from the base plate and is pressed onto the sample material, generating resistance against an 822g spring. Each 0.0254 mm of deflection of the indenter is shown as 1 degree Shore (A), therefore, the harder the material, the more the deflection, the higher the number.

Measuring IRHD (International Rubber Hardness Degrees)