An improved method of making an ethylene acrylate (AEM) elastomer or a polyacrylate (ACM) elastomer wherein an aqueous solution of hexamethylene diamine (HMDA) is employed as the curative agent rather than hexamethylene diamine carbamate (HMDAC). The HMDA reacts with the curative-site monomer derived from the monoalkyl ester of a 1,4-butene-dioic acid in the presence of water, producing (i.e., after press-curing and any secondary heat-curing) a crosslinked elastomer with properties essentially indistinguishable from that produced using HMDAC as the curative agent. Advantageously, the aqueous solution of HMDA can be blended directly into the compound or it can be deposited on an additive such as silica or carbon black prior to blending. Elastomers produced by the improved method according to the present invention are particularly useful in automotive applications requiring oil resistant compositions.