A PTFE seal and method of fabrication therefor includes preparing a mixture of PTFE resin powder and a susceptor material which is then compacted and sintered by exciting the susceptor material with microwave energy. The compositions are basically comprised of water, an aqueous rubber latex, an organophillic clay, sodium carbonate, an epoxy resin and a hardening agent for said epoxy resin. The concave mirror is precisely aligned to the core of the fiber.