The flat crush test (1) is a measure of the resistance of the flutes in corrugated board to a crushing force applied perpendicular to the surface of the board under prescribed conditions. The test is satisfactory for single-faced or single wall (double-faced) corrugated board, but not for double-wall or triple-wall corrugated board, because of lateral motion of the central facing or facings. In this method the specimen rests on an essentially rigid support and is tested at a constant strain rate. TAPPI T 808 Flat Crush Test of Corrugated Board describes a procedure in which the specimen rests on a flexing support and is tested at a constant rate of loading.