1.1 ,This test method covers the use of a sealed cavity rotorless oscillating shear rheometer for the measurement of the softening effects of rising sinusoidal strain when applied to an unvulcanized rubber compound containing significant amounts of colloidal fillers (such as silica or carbon black, or both) from a rubber mixing procedure. These strain softening properties relate to mixing conditions, the composition of the rubber compound, colloidal particle (Payne Effect) characteristics of the fillers, and in some cases the degree of reaction between an organosilane and precipitated, hydrated silica during mixing. This procedure is being commonly applied to rubber reactive mixing procedures.