GLAZES, POTTERY
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Pottery glazes are comprised of metal salts or oxides, which when fired give the distinctive colour to pottery items. Many glazes contain heavy metals.
In the past, most glazes used were the oxide of the metal, many of these e.g. lead oxide and cadmium oxide are very toxic if ingested.
Many glazes are now provided as sintered glass, where the metal oxide has been fired with silica to make a glass, which is crushed, for use as a glaze. Sintered glass is much safer to use than the pure metal oxide. The only glazes approved for use in DET schools as those purchased via Q-Stores, which have no cadmium, and lead levels are less than 0.1% of dry weight.
DET schools wishing to use other proprietary glazes must ensure a chemical analysis has been undertaken to ensure the lead content is less than 0.1% of dry weight. A memorandum to principals has been issued on this matter. (Memorandum 95/088)Glazes should not be used by students Years K-2 or with students exhibiting 'pica' (those who eat substances other than food). Disposal: Solid waste pottery glazes may be disposed of in the garbage (to landfill).
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