Can this glaze be used on domestic ware? Has it been tested for dishwashers/microwaves?
If a glaze is food safe our not depends on several factors including the type of clay used, the firing temperature, the shape of the vessel, the thickness of glaze even the position of the vessel in the kiln can have an effect on the glaze. Ideally a food safe test would be carried out by a reputable body like British Ceram. In the case of the glaze mentioned it is unlikely it would pass a food safe test as bacteria can can easily grow in the craze marks left in earthenware glazes. The most suitable glazes for functional ware are stoneware and glossy fired in an electric kiln and to the suggested temperatures.