Full definition
Resistance to deformation of seal material measured on the Shore A scale. Standard O-rings: 70 Shore A. High-pressure applications: 90 Shore A to resist extrusion. Piston seals: 90-95 Shore A. Lip seals: 70-80 Shore A. Higher hardness = less deformation under load but greater friction force and reduced ability to seal imperfect surfaces. Tested per ASTM D2240.