A modeling material consisting of finely ground particles of colored polymer, often polyvinyl chloride (PVC), held together by a binder to form a malleable clay-like medium. Trademarked brand names include FIMO and Sculpey. In oven-fired polymer clays, finished articles are heated in a domestic oven to fire or fuse or sinter the polymer molecules into a hard, durable object ? often jewelry, beads, or small sculptures. Because polymer clays are made of self-colored molecules, making them bleed-proof: different colors do not bleed into each other when placed against each other.MEDICAL ALERT!Baking any art material in an oven also used for food carries the risk of contaminating food. Use a separate oven that has reliable temperature control and only bake polymer clays to the manufacturer's recommended hardening temperature. Obtain the Material Safety Data Sheet (MSDS) from the manufacturer or supplier, and make sure the temperature of decomposition is not reached. Do not use hardening modeling clays that have DEHP as a plasticizer, because, at this time (2004), the longterm hazards of replacement plasticizers have not been adequately researched. Use polymer clays either outdoors or in front of a window exhaust fan.Also see modeling clay and modeling tools.