Masonry oven India, tandoors are traditional clay ovens, although these days modern electrically fired tandoors are available. The open-topped tandoor is a transitional design between the earth oven and the Roman-plan masonry oven. In the precolumbian Americas, similar ovens were often made of clay or adobe and are now referred to by the Spanish term "horno" (meaning "oven"). Horns are also traditional in the American Southwest. The traditional direct-fired masonry design is often called a "Roman" or "black" oven and dates in Western culture to at least the Roman Republic. It is known as a black oven because the fire generates soot
Ceramic glaze 2012, over 650 ceramic manufacturing establishments were reported in the United States. Floor tile, wall tile, sanitary-ware, bathroom accessories, kitchenware, and tableware are all potential ceramic-containing products that are available for consumers. Heavy metals are dense metals used in glazes to produce a particular color or texture. Glaze components are more likely to be leached into the environment when non-recycled ceramic products are exposed to warm or acidic water. Leaching of heavy metals occurs when ceramic products are glazed incorrectly or damaged. Lead and chromium are two heavy metals commonly used in ceramic glazes that are heavily monitored by government