Shore-hardness

Shore hardness is often used in the quality control of adhesives to ensure that products meet requirements. It can also be helpful in material selection and new product development to determine hardness and thus suitability for certain applications.

It is named after its inventor Albert Ferdinand Shore and is determined by penetrating a special test probe into the material. Shore hardness is one of the most common methods of determining hardness using the Shore durometer because it is quick and easy to perform.

The durometer measures the depth of an indentation in the material created by a given force on a standardised indenter. This depth depends on the hardness of the material, its viscoelastic properties, the shape of the indenter and the duration of the test.

The Shore hardness is given on a scale from 0 to 100. A value of 0 corresponds to a material that has no resistance to penetration by the test probe, while a value of 100 corresponds to a very hard material.

There are several durometer scales used for materials with different properties. The two most common scales, which use slightly different measuring systems, are referred to as Type A and Type D.

• Type A is used to test soft materials and materials such as silicones with a truncated cone.
  
  
• Type D is used to test hard materials and materials such as epoxy, PU and a tapered test probe.

In each case, the depth of penetration of the test tip is measured and converted into a Shore hardness value. The measurement is usually made on the surface of the material, as it is most affected by influences such as temperature and moisture.