Shore hardness

A surface hardness measurement made with a handheld impressor that presses a sharp steel indenter into the material, standardised in ASTM D2583 and EN 59. In the composites industry it is widely used as a quick workshop or site check of laminate and gelcoat cure, since readings rise as the resin hardens.

A flexible material applied to joints and interfaces to exclude water, air or other media while accommodating movement between the parts, in contrast to an adhesive whose primary job is to transfer load. Silicone, polyurethane, polysulphide and silane-modified polymer chemistries dominate construction and industrial sealing.

Ethylene propylene diene monomer (M class) rubber, a synthetic elastomer with excellent resistance to ultraviolet light, ozone and weathering. In roofing it is used as a single-ply waterproofing membrane, often supplied in large prefabricated sheets, and it is also widely used for seals, gaskets, hoses and glazing profiles in the automotive, marine and industrial sectors.