There are three types of clay used in ceramics today:
Earthenware: porous clay most frequently found in nature. Due to a high percentage of iron and other mineral impurities, earthenware is fired at a lower temperature. The color of fired earthenware varies from tan to red to black.
Stoneware: less porous than earthenware and bonds well with glazes. The color of fired stoneware tends to be variegated, ranges from buff to light gray to dark gray.
Porcelain: or kaolin is made of tinier particles than stoneware and earthenware and is also known as china clay. Chinese potters have used kaolin combined with other clays for hundreds of years. Porcelain is a dense, white clay that can be manipulated into extremely thin, smooth, translucent pieces.
To form beads, artisans shape wet clay by hand. More intricate beads, are made with molds and carving tools. The beads are set in the open air until they are completely dry "greenware" and ready for "bisquing", the first kiln firing. This process burns out the remaining water. The beads become very porous and more durable, which allows the glazes to take hold. The temperature of the bisque firing depends on the type of clay: earthenware requires temperatures beginning at 1300 degrees F, while porcelain fires at temperatures above 2300 degrees F.
After the bisque firing, beads are ready for glazing. Designs may be painted on by hand or decals may be applied before the beads are dipped in glaze. There are many different glaze "recipes," but all are made from combinations of minerals. Some glazes may also contain metallic oxides. Once glazed, beads are ready for the final firing.
There are two methods of final firing:
High-fire Method: uses a kiln that is hot enough to melt the glaze into the beads, fusing the glassy coating to the surface. Beads are suspended on rods to prevent the glaze from settling improperly. This method takes many hours, since the kiln must heat up and then cool down slowly to prevent pieces from warping or cracking. Multi-colored pieces may be coated with multiple layers of glaze, each fired at a successively lower temperature.
Raku Method: is a traditional Japanese technique, where beads are removed from the kiln while still red-hot and plunged into a metal container filled with combustible material, such as pine needles, dry leaves or sawdust. These combustible materials burst into flame and the container is covered so that the fire consumes the oxygen reducing the glaze and coating the bead with soot. Then the beads are quick-cooled in water, and the soot is rubbed off by hand. If a temperature-sensitive crackle glaze has been used, the soot remains in the cracks after the glazed area has been cleaned. The raku process is often used in combination with copper luster or copper matte glazes, giving the finished beads a rough-textured or "oxidized" look.
In both firing methods, slight variations in temperature and duration of firing can significantly impact the color intensity of a glaze. Different batches of the same material vary in color and it is often difficult to replicate a specific hue.
to some more great options of ceramic beads, simply go to www.big-baby.com were you can see our collection! if you have a special occassion and would like to create something special just for you, we can provide that as well! the options are only limited as your imagination!
Content Provided in Part by: All About Beads, by Maureen Murray, B.T. Batsford Ltd ; Keith O'Connor; Golem Design Studio; and http://www.claytimes.com .
Earthenware: porous clay most frequently found in nature. Due to a high percentage of iron and other mineral impurities, earthenware is fired at a lower temperature. The color of fired earthenware varies from tan to red to black.
Stoneware: less porous than earthenware and bonds well with glazes. The color of fired stoneware tends to be variegated, ranges from buff to light gray to dark gray.
Porcelain: or kaolin is made of tinier particles than stoneware and earthenware and is also known as china clay. Chinese potters have used kaolin combined with other clays for hundreds of years. Porcelain is a dense, white clay that can be manipulated into extremely thin, smooth, translucent pieces.
To form beads, artisans shape wet clay by hand. More intricate beads, are made with molds and carving tools. The beads are set in the open air until they are completely dry "greenware" and ready for "bisquing", the first kiln firing. This process burns out the remaining water. The beads become very porous and more durable, which allows the glazes to take hold. The temperature of the bisque firing depends on the type of clay: earthenware requires temperatures beginning at 1300 degrees F, while porcelain fires at temperatures above 2300 degrees F.
After the bisque firing, beads are ready for glazing. Designs may be painted on by hand or decals may be applied before the beads are dipped in glaze. There are many different glaze "recipes," but all are made from combinations of minerals. Some glazes may also contain metallic oxides. Once glazed, beads are ready for the final firing.
There are two methods of final firing:
High-fire Method: uses a kiln that is hot enough to melt the glaze into the beads, fusing the glassy coating to the surface. Beads are suspended on rods to prevent the glaze from settling improperly. This method takes many hours, since the kiln must heat up and then cool down slowly to prevent pieces from warping or cracking. Multi-colored pieces may be coated with multiple layers of glaze, each fired at a successively lower temperature.
Raku Method: is a traditional Japanese technique, where beads are removed from the kiln while still red-hot and plunged into a metal container filled with combustible material, such as pine needles, dry leaves or sawdust. These combustible materials burst into flame and the container is covered so that the fire consumes the oxygen reducing the glaze and coating the bead with soot. Then the beads are quick-cooled in water, and the soot is rubbed off by hand. If a temperature-sensitive crackle glaze has been used, the soot remains in the cracks after the glazed area has been cleaned. The raku process is often used in combination with copper luster or copper matte glazes, giving the finished beads a rough-textured or "oxidized" look.
In both firing methods, slight variations in temperature and duration of firing can significantly impact the color intensity of a glaze. Different batches of the same material vary in color and it is often difficult to replicate a specific hue.
to some more great options of ceramic beads, simply go to www.big-baby.com were you can see our collection! if you have a special occassion and would like to create something special just for you, we can provide that as well! the options are only limited as your imagination!
Content Provided in Part by: All About Beads, by Maureen Murray, B.T. Batsford Ltd ; Keith O'Connor; Golem Design Studio; and http://www.claytimes.com .
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