A gasket elastomer precursor of admixed fluoroelastomer particulate, curing agent, and metallic oxide reduction-agent optionally admixed with any of microspheres, inert particulate, PTFE particles. In one embodiment, the composition is applied to a substrate and cured to provide a fuel cell gasket. The admixtures provide a basis for designed cured admixtures having internally differentiated regions interbonded by cured elastomer.