Living dangerously: barium glaze research project

Abstract

ISSN 0967–9782 to metallic barium and other barium compounds, including barium oxide, hydroxide, peroxide, and a variety of salts. Barium compounds are used widely in industry and medical science ‘as loaders for paper, soap, rubber and linoleum, as drilling muds in oil rigs, in the manufacture of valves and in the production of lights and green flares .. . as pigments in the manufacture of paints; in cement where concrete is exposed to salt water; in the radio industry to capture the last traces of gases in vacuum tubes; in the ceramic and glass industries; as insecticides and rodenticides; as extinguishers for radium, uranium, and plutonium; and as contrast material in X-ray medical examination’.1 Barium sulphate is the source of most Ba compounds but barium carbonate 3 ) is used both in the ceramic industry and to make barium fluoride. It has sometimes been suggested that for use in pottery glazes, barium sulphate 4 ) should be substituted for 3 due to its lower solubility (Table 1).2 It should be remembered that the ultimate toxic agent is the barium ion, and so the relative toxicity of barium compounds is directly related to their ability to dissolve or form ions. This can cause problems with the burning off of the sulphur dioxide from the glaze during firing resulting in pinholing. In some cases the substitution may be satisfactory, and so the danger to the potter using the barium can be lessened, but it does not help the problem of barium leaching from glazes used on domestic ware and thus the danger to the user.