A vitreous coating applied for practical and ornamental purposes to earthenware, consisting of powder of lead oxide with POISONOUS!silacious sand, salt and potash which fuses when fired. It is transparent but color can be added. Because of lead's toxicity, lead glazes must never be used on surface which might ever contact food, drink, or a mouth; and containers of lead glazes must be labeled with such warnings. All glazes should be labeled to reflect their lead and cadmium content. The following chart describes six different types of ceramic glazes, each carrying levels of concerns about lead content, in order to help you to determine which are safe to use on dinnerware ? vessels for food or drink.1. Dinnerware safe. Contains no lead.2. Dinnerware safe. Contains some lead, but passes release tests.3. Contains lead. Not recommended for surfaces which contact food or drink.4. Contains no lead. Not recommended for food because of soft nature of the glaze.5. Contains no lead, but does not pass lead and cadmium release due to soft nature of the glaze.6. Contains lead bearing ingredients. We do not recommend these glazes on surfaces that contact food or drink.A similar criterion should be followed whenever glazes contain the toxic element cadmium.Also see ceramics, glaze, poison, and vessel.