The individual particles of these stains have been embedded into refractory grains of zirconia to enable them to resist being taking into solution in the melting glaze. They thus have a recommended maximum firing temperature and time. This strategy makes it possible to use materials like cadmium with less potential leaching in the fired glaze. However large percentages of these stains must be added to a glaze to achieve the color and they are very expensive.
Although these are zirconium encapsulated the manufacturers still say: The product is considered to be hazardous under OSHA standard 29 CFR 1910.1200. It is a skin, eye, and respiratory irritant.
|Hazards||Zirconium Compounds Toxicity|