What is Shore Hardness?
Shore hardness is a method of determining the hardness of elastomers. It is a universal scale used to measure the solidity of materials, ranging from super-soft gels, to flexible rubbers and rigid plastics.
It was named after Albert Ferdinand Shore who developed the Shore durometer in the 1920s to measure the hardness of rubber.
How is Shore Hardness Measured?
To measure the Shore hardness, a handheld device called a durometer is used. A durometer uses a spring-loaded indenter to measure the depth of indentation in a material. The indentor is placed on the surface of the material and pressure is applied, measuring the resistance of the material.
The higher the number reading on the durometer, the greater the resistance; making this higher on the Shore hardness scale. The lower the reading, the less resistance; making it a softer material and lower on the Shore hardness scale.
What is the Difference Between Shore 00, Shore A and Shore D Hardness?
There are several different Shore scales, such as Shore 00, Shore A and Shore D. The difference between each Shore scale relates to the hardness of the material being measured. Each scale ranges from 0 to 100, with 0 being the softest and 100 being the hardest.
Shore 00 is less common and used for very soft materials, such as super soft gels. Shore A is used for soft materials such as flexible rubbers, while Shore D is used for harder materials, such as rigid rubbers.
An example of a material measured on the Shore 00 scale is Platsil Gel 00, while a Shore A material is Ad-Sil 20, and an example of a material measured on the Shore D scale is EasyFlo 120.
Why is Shore Hardness Important?
Shore hardness plays a crucial role in mould making because it impacts part demoulding and mould durability.
Softer moulds (those with a lower Shore OO or A number) are more flexible making it easier to extract delicate or intricate parts without risk of damage. Harder moulds (those with a higher Shore D number) provide better stability and resist wear and tear during repeated casting cycles, as well as being useful for moulds used with abrasive materials.
To achieve optimal results it is important to select the right Shore hardness for your mould material, taking into account factors such as part geometry, casting material and number of casts.
Most commonly, material is decided upon selecting an appropriate shore hardness; a flexible rubber will easily demould fragile model parts as opposed to a firmer, rigid material.
If you have any technical questions on Shore hardness and how it is measured, please contact us or call 01638 750 679 (international clients: +44 01638 750 679). At Mouldlife | PS, we have many years of experience. We also have several members of staff currently working within the industry who would be more than happy to assist with your queries.