A source of barium oxide, a flux which increases refractive index imparting brilliance to gloss glazes. It can also be used to produce striking blue matte glazes with copper and cobalt oxides. It is toxic by ingestion. similar glaze results are possible by replacing 100 g barium carbonate with 75 g strontium carbonate. For more information on barium carbonate, see the Digitalfire.com Reference Library of ceramic materials.