Pottery is regularly made of clay, which can be molded into a range of shapes while wet. Once the form has been established, the piece of porcelain is placed in a hot kiln, where the high climatic characteristic hardens the clay and gives it permanence. In order to give porcelain and porcelain a smooth, shiny finish, one of several glazes must be applied. It can also be used to make some kinds of porcelain less porous.
An underglaze is a type of glaze used to spin the embellishment applied to pottery, while an overglaze is used to create a shiny outside over the decoration. Not only does the overglaze contribute a protective layer, it also leaves colors vibrant. When using this type of glaze, the piece of porcelain is first "fired" in a kiln, the overglaze is applied, and the item is then re-fired. The heat helps to blend the color pigments with the glaze and creates a glass-like, shiny surface.
Duncan Ceramic
Ceramic glazes regularly consist of silica, a component of quartz. Normally, a very high heat is required to melt quartz, so a "flux" is added to the glaze. Flux is a substance that lowers the melting climatic characteristic of a single mineral or mixture so it can be fired at a lower heat, the most coarse of which are lead, potassium, sodium, lime and calcium oxide. Pieces of porcelain can be dipped into the glaze, sprayed or the glaze can be applied with a brush. Glaze can also be poured directly over the pottery.
Lead glazes have existed for centuries, although some controversy exists over its use. Many potters claim that they cannot achieve the proper color shade or glow without the use of a lead glaze, while others argue that lead is not an suitable alternative for household use. It is often strongly suggested that, as a protection precaution, consumers refrain from purchasing cookware or dishes that consist of a lead coating. Even edible plants are susceptible to acquiring lead residue if grown in a container glazed with lead.
It also helps to know the origin of a piece of pottery, as underdeveloped countries do not yet understand the implications of using lead and sometimes fire their pieces at low enough temperatures that would allow toxic release into food or drink.
Pottery containing alkali glazes, using salt and/or potassium, have also been found throughout history; it is not unusual to find a piece that features a glazed mix of lead and alkali. Regardless of the type of glaze chosen, porcelain is regularly fired at temperatures between 950 deg C and 1430 deg C. Glazes are found on a range of household items, together with toilets and sinks, tableware, figurines and giftware, and tiles.
Why Glaze Type is leading
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