Process for vulcanization of elastomer products

A process for vulcanization of elastomer products which comprises the steps of heating under pressure, the elastomer product mounted in a metal mold by supplying thereto vulcanizing medium, suspending the supply of said vulcanizing medium when said elastomer product has reached a predetermined temperature or passed through a predetermined time period, subsequently supplying inert gas preliminarily extracted from atmospheric air with use of molecular sieves, and maintained at least under approximately the same pressure as that of said vulcanizing medium as a heat retaining medium, up to the termination of remaining time period for the heating step so as to maintain the elastomer product at said predetermined temperature, and, upon termination of said heating step, restoring a mixture of the inert gas and the vulcanizing medium so as to derive the inert gas through steam separation for re-utilization of said inert gas for a preshaping of the elastomer product prior to the vulcanization of said elastomer product and the like.