What is Shore Hardness?

Shore hardness (AKA Shore durometer) is the term used to describe the hardness of a material. On a scale of 0 to 100, a higher number represents a harder material.

With hardness defined as the material’s resistance to indentation, a specialised tool called the durometer is used to determine hardness. The durometer has a pin on one end and when pressed onto a material, it measures the indentation which translates to a relevant Shore value.

Photo : Indenter on a Shore A durometer

Shore values range between 0 to 100 with many different Shore types. In the rubber industry, the most commonly used term is Shore A. Some examples are Shore D and Shore OO durometers. Shore D is designed to measure hard and solid materials, some examples are bowling balls, hockey pucks and plastics. Whereas Shore OO is used on very soft materials like light foams, sponges and rubber gels. Different material types requires its own type of durometer, if used incorrectly, the reading will be inaccurate.

Photo : Measuring the hardness of our Silicone Seal

Other than using the correct durometer, proper technique must be observed to ensure an accurate Shore hardness measurement. At ARIS Performance, we follow these 3 simple rules.

- THICKNESS OF MATERIAL

1/4” (6mm) is the minimum thickness. A durometer measures hardness by the indentation depth into the material. If the material is too thin, the indenter or pin on the durometer will be affected by the surface that the material is placed on.

- READ DUROMETER IN 1 SECOND

For standard hardness measurement, take the readings in 1 second of applying pressure for an accurate measurement. Of course, if a timed duration Shore measurement is required for your application, then take the measurements at the stipulated timings.

- AVOID SUDDEN MOVEMENTS

When applying pressure with the durometer into the material, ensure that the application force is consistent, without shock. If strict measurements are needed, it is recommended to mount the durometer onto an operating stand.

If you would like a custom silicone rubber product to your own specific Shore Hardness value, get in touch with us and we'll help!

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