Hysteresis is a measure of the amount of energy lost per cycle during deformation of an elastomer. Tangent delta, or the loss factor, is a measure of hysteresis and is the ratio of the loss modulus to the storage modulus. Tangent delta is strongly influenced by the choice of polymer. The addition of carbon black significantly increases tangent delta in rubber compounds. Plasticizers may slightly increase tangent delta but in some cases, they can significantly reduce tangent delta. In natural rubber compounds, the choice of accelerator and the amount of sulfur in the cure system did not have much impact on damping.