Purge ZR (Zirconia Furnace Decontaminator) is a double-activated ion and oxide-absorbing material that eliminates contaminates that can cause discoloration and porcelain delamination in zirconia copings. For example, the low levels of radioactive materials found in zirconium can build up inside a muffle and cause color problems; with Purge ZR, these radioactive isotopes are absorbed completely out of the furnace. Purge ZR should be used once a week in zirconia alumina or firing furnaces to extend muffle/thermocouple life and maintain thermocouple accuracy. From VISION USA, a Dentrex Co., the Purge ZR kit with Ceramic Crucible contains enough material for 25 cleanings.