Rechtliche Und Ethische Aspekte by Susan 4.
A potter at work in Jaura, Madhya PradeshIndia Clay ware takes on varying physical characteristics during the making of pottery.
Greenware refers to unfired objects. At sufficient moisture content, bodies at this stage are in their most plastic form they are soft and malleable, and hence can be easily deformed by handling.
Leather-hard refers to a clay body that has been dried partially. Clay bodies at this stage are very firm and only slightly pliable. Trimming and handle attachment often occurs at the leather-hard state. At that moisture level, the item is ready to be bisque fired. Bisque   refers to the clay after the object is shaped to the desired form and fired in the kiln for the first time, known as "bisque fired" or "biscuit fired".
This firing changes the clay body in several ways. Mineral components of the clay body will undergo chemical changes that will change the colour of the clay. Glaze fired is the final stage of some pottery making.
A glaze may be applied to the bisque form and the object can be decorated in several ways. After this the object is "glazed fired", which causes the glaze material to melt, then adhere to the object.
The glaze firing will also harden the body still more as chemical processes can continue to occur in the body. Clay bodies and mineral contents[ edit ] Preparation of clay for pottery in India There are several materials that are referred to as clay. The properties which make them different include: Plasticitythe malleability of the body; the extent to which they will absorb water after firing; and shrinkage, the extent of reduction in size of a body as water is removed.
Different clay bodies also differ in the way in which they respond when fired in the kiln.
A clay body can be decorated before or after firing. Prior to some shaping processes, clay must be prepared. Each of these different clays are composed of different types and amounts of minerals that determine the characteristics of resulting pottery.
There can be regional variations in the properties of raw materials used for the production of pottery, and this can lead to wares that are unique in character to a locality.
It is common for clays and other materials to be mixed to produce clay bodies suited to specific purposes. A common component of clay bodies is the mineral kaolinite.
Other mineral compounds in the clay may act as fluxes which lower the vitrification temperature of bodies. Following is a list of different types of clay used for pottery.
Ball clay An extremely plastic, fine grained sedimentary clay, which may contain some organic matter. Small amounts can be added to porcelain to increase plasticity. Fire clay A clay having a slightly lower percentage of fluxes than kaolin, but usually quite plastic.
It is highly heat resistant form of clay which can be combined with other clays to increase the firing temperature and may be used as an ingredient to make stoneware type bodies. Stoneware clay Suitable for creating stoneware. This clay has many of the characteristics between fire clay and ball clay, having finer grain, like ball clay but is more heat resistant like fire clays.
Common red clay and Shale clay have vegetable and ferric oxide impurities which make them useful for bricks, but are generally unsatisfactory for pottery except under special conditions of a particular deposit. Methods of shaping[ edit ] A man shapes pottery as it turns on a wheel.This ware was copied in Germany, the Netherlands, and England.
as in the Roman pottery known as terra sigillata, faience, and delft. Unfortunately, these are variously defined by various authorities.
The art of tin-glazing was discovered by the Assyrians, who used it to cover courses of decorated brickwork. Terra sigillata is a type of fine Roman ceramic known for its relief decoration and smooth red slip.
The vessel and decorations were formed in a mold and were sometimes embellished with stamps, roller-dies, appliqués, barbotine, and incision.
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Austria Including Hungary, Transylvania, Dalmatia, And Bosnia Handbook for Travellers () - Karl Baedeker. The firing of the ware that results in the biscuit article causes permanent chemical and physical changes to occur.
These result in a much harder and more resilient article which can still be porous, and this can ease the application of glazes. Unfired "green ware" pottery on a traditional drying rack at Conner Prairie living Terra Sigillata is an ancient form of decorating ceramics that was first developed in or by pouring the underglaze into the mold, covering the inside, creating a swirling effect, then the mold is filled with slip.
In-glaze decoration; On-glaze. In the midth century, English potters invented bone china, a somewhat harder ware that gained whiteness, translucency, and stability through the inclusion of calcium phosphate in the form of calcined (fired, chemically altered) oxbones.
The clay can be flattened and then shaped by being pressed against the inside or outside of a mold—a.