Barium Carbonate – BaCO3 (m.p. 2480o F/1360o C) is used in glazes as the typical source for Barium. It has limited use due to its lack of reactivity and toxicity. In low fire glazes (cone 06-5) it promotes matt finishes. At high temperatures (cone 8-13), it is a powerful flux. It is used in clay bodies to control scumming by causing sulfates to be insoluble.