how ceramics are made?

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traditional ceramics are made from earthy materials clay,sand,or ground rock that have been subjected to high temperature. heat binds the materials together and hardens them. most ceramics share certain qualities. they resist heat,pressure,corrosion,and moisture. several kinds of clay are used to make ceramics. common clays,which contain many impurities,are used chiefly in brick making. kaolin clay is the purest type of clay. it is used to make fine china and porcelain. when fired,it turns a pure white. fire clays have a slightly different mineral composition. they can withstand high temperatures,manufacturers often mix powder minerals into clay to produe specific qualities in their products. the clay and other materials are then mixed with water. just the right amount of water must be added if there is too much,the clay will be too soft to hold its shape. it there is too little, the clay will be stiffed and difficult to shape. individual pieces of pottery can be shaped by hand on a potters wheel. but manufacturer used several methods to make many copies of the same object. in slip casting, a mixture of clay and water is poured into a plaster mold of the object. the mold absorbs the water and retains a thin coating of clay on the insiede. more and more of the mixture is poured in,and the clay coating becomes thicker. when the coating is thick enough, it is allowed to harden. then it is lifted out of the mold and trimmed,or fitted. another method of forming ceramics is jiggering. this method of plaster mold is used to shaped once surface of the article for instance,the upper surface of a plate or the outside surface of a cup or bowl. the mold rotates,just as a pooters wheel does. clay is force down unto the spinning mold,so that it takes the shape of the molf of one surface. the other surface is shaped by a tool mounted on a lever. a third method of shaping clay ceramics is to press the clay directly into a mold. ceramic pipe and bricks are formed by a fourth method extrusion. in this method, the clay is force through the opening of a dye shaping tools. after the piece has been formed it is trimmed and dried. it is then ready for firing. this is done in a kiln a special furnace for heating and hardening ceramics. high temperatures are needed,raging from about 1200-3270 fahrenheit the length of firing as just important as the temperature. the clay is fired for varying periods of time depending on its ingredients and on the product being made. glaze are transparent,glossy coating that are applied to the surface of many ceramics products often firing. they do two things they beautify the object,and they prevent it from absorbing liquids. after the glazed is applied the article is fired again.