Two ranges of Shieldseal elastomers specially developed for use with ionising radiation have been introduced by James Walker, backed with evaluation results from independent test houses and individual customers in the nuclear sector. Shieldseal 500 is a range of three lead-free elastomers for shielding x-ray and gamma radiation. These materials comprise specially formulated metallic filters evenly dispersed throughout a base of either ethylene-propylene (EPDM) or polychloroprene (CR) elastomers. They are designed for duties where a resiliant rubber based flexible seal is needed to prevent shine paths in active areas. Shieldseal 600, meanwhile, is a range of four elastomers formulated to resist ionising radiation. Each material is available as mouldings or cut gaskets. When irradiated with gamma radiation, they retain compression-set resistance, and offer long service life and value for money.