Shore Hardness
Also called: Shore A, Shore D, durometer hardness
Shore hardness measures how resistant a plastic or rubber is to indentation, on Shore A for soft materials and Shore D for harder ones.
Shore hardness is a measure of a material resistance to indentation, read with a durometer. The Shore A scale is used for soft materials such as TPR, flexible PVC and EVA foam, while Shore D is used for harder plastics. The test follows standards such as ASTM D2240 and ISO 868.
Why it matters when buying recycled plastic
- For soft materials, hardness is often the most useful specification, more so than the polymer name alone.
- Agree a hardness range, for example a band on the Shore A scale, and test a moulded sample, not just granules.
- Recycled flexible PVC can lose plasticiser over its life, so it may be harder than the original product.
- Mixing scrap of different hardness gives an average that may not suit your product; ask suppliers to keep lots separate.
How it is measured
A spring-loaded indenter is pressed into a flat sample of specified thickness, and the reading is taken after a fixed time. Readings depend on temperature and sample thickness, so compare results measured under the same conditions. Include hardness in your RFQ for soft compounds.