The physical tests obtainable from silicone rubber comprising dimethylsiloxane have now been raised from less than 600 pounds per square inch tensile strength and 250 percent elongation to approximately 2000 pounds per square inch tensile strength and 500 percent elongation. These results have, it is true, been obtained with only one pigment; but the important point is that silicone rubber need no longer be avoided and discarded for those applications where strength or resistance to wearing and abrasion are necessary. Silicone rubber like the butadiene-styrene copolymers does not crystallize readily and consequently exhibits little or no strength in the unreinforced state. Therein, of course, lies the secret of its excellent low temperature properties. It is proven now that reinforcement of silicone rubber with a proper pigment will provide ample strength.