Saving Your Treasures: Ceramics
Types of Materials
Ceramics are made from clays with varying composition. Modifiers and colorants are added to alter the appearance and properties of the finished ceramic. The clay mixture, also called the body, is shaped using a variety of techniques including turning, coiling, and molding. The shaped objects are heated in a kiln to drive off water and realign the crystalline structure of the clay. The clay becomes compacted and, in some cases, begins to melt during firing.
Common clay bodies are earthenware, stoneware, and porcelain. Earthenware is porous, often coarse-bodied, and has been fired at a relatively low temperature. Stoneware is also often coarse-bodied, but is fired at a high enough temperature that the stoneware body is impermeable to water, even without a glaze. Stoneware can also be smooth-bodied,as in Wedgwood Jasperwares, which are not glazed.
Porcelains are fine-bodied ceramics that are fired at very high temperatures to create a glass-like, vitrified body. Porcelain bodies fuse with the glaze layer during firing. They are very strong and, as a result, can be made very thin.
Ceramics are usually decorated with colored slips and glass slurries. The slips and slurries applied contain ground, glassy materials that melt upon firing to form a glaze. Colorants and other minerals are used to modify the glaze to produce different colors and effects.
Origins & Properties
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TYPES OF MATERIALS