unvulcanized

Updated: February 25, 2026

Finally, rubber recovered by the chemical process, it is claimed, is harder than that obtained by any other; so that it is usual to add, during vulcanization, in order to soften the product, the residuum obtained from petroleum manufactures, or palm or other oils. Unvulcanized rubber clippings also have been used for this purpose.

Various - Scientific American Supplement, No. 1178, June 25, 1898