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Different Types Of Clay.

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Allison Garnett 12.6. Sculpture Written Assignment. Different Types Of Clay. The two most commonly used clays are; Earthenware Clays. Through out history earthenware clays have been used for domestic ware, today earthenware is used for both decorative and functional ceramics. Earthenware clays are usually fired between 1970'f - 2100'f (1080'c - 1150'c) these remain porous even after firing. Earthenware clays contain minerals, which would melt at higher temperatures, making the shapes bloat and distort. Earthenware clay is usually white, buff, pink, red or brown dependant on the iron oxide content. Stoneware Clays. White rich, brightly coloured glazes are possible at stoneware temperature. This area of ceramics is more commonly associated with subdued subtle greys, pale greens and rich blacks. Stoneware clays are usually fired between 2190'f - 2460'f (1200'c - 1350'c). Stoneware clays do not have the large amounts of fluxes found in earthenware, so they can be fired up to the point where the clay softens. ...read more.


Also known as 'soft glazes.' They mature below 1150'c / 2102'f, and are used to cover a porous body. The typical Earthenware glaze is shiny and smooth; it can be transparent or white and fully opaque, the latter providing a background for bright clear colours. The formulas for Earthenware glazes differ from those of stoneware and porcelain mainly in there choose of bases, and in the ratio of base to silica. Other popular glazes are; Porcelain glazes. The particular quality of a porcelain glaze is that both the body and glaze mature and fuse together to give a tough translucent body. Translucency depends on the composition of the body, and while it is possible to obtain a wide range of colours and effects on porcelain, the desired effect is often to enchance the particular quality of the body by using a transparentglaze. The glaze for porcelain should reflect the fine quality of the ware and therefore it should be finer than a stoneware glaze that suits a more robust body. ...read more.


Impressing, Engraving. A design cut into clay usually with a wooden or bamboo tool cut to an angle or to a rounded point. This is preferable to a sharp metal point, which will give a weak and furrowed line. The decoration can be enhanced by an overlay of slip or a dry usually, ash glaze. Firing Processes. Firing is the heat treatment of ceramic materials at least to the sintering stage. Types of firing: Stoneware Firing. High temperature firing. The generally accepted minimum is 1200'c / 2195'f and the range is 1200'c - 1350'c. Bodies with artificially lowered vitrification points have been marketed. Biscuit Fire. The greatest risk of breakage or explosion occurs in the 194'f - 302'f range. Thick pieces are obviously more at risk than thin walled ware. Raku Kiln A raku kiln must satisfy the following conditions it must reach 800'c / 1472'f and unless it is used for one special piece at a time, maintain that temperature for several hours, the chamber must be readily accessible and easily opened and closed with the kiln at full temperature; reasonably oxidizing conditions must prevel. ?? ?? ?? ?? 1 ...read more.

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