This International Standard specifies, for general-purpose chloroprene rubbers (CRs): — physical and chemical tests on raw rubbers; — standard materials, standard test formulations, equipment and processing methods for evaluating the vulcanization characteristics. General-purpose chloroprene rubbers fall into three broad classes based on the type of polymerization modifier used in their preparation: a) sulfur-modified types; b) mercaptan-modified types; c) types modified by other products. For class c), the procedure for either a) or b) may be followed.