|
Buckingham tea saucer
Bone china Bone china is a kind of porcelain body initially produced in the UK in which calcined ox bone, bone ash, is an important part. It is distinguish by high whiteness, translucency and strength. buckingham tea saucer may be an example of this process. The first use of bone ash in ceramics is credited to Thomas Frye in the mid eighteenth century in which he used it to make a type of soft-paste porcelain. In Towards the end of the eighteenth century, Josiah Spode undertook further developments, and consequently popularised it, by mixing it with kaolin, China stone and china clay to compete with the imported Oriental porcelain. The original basic formula of six parts bone ash, three and a half parts china clay, and four parts china stone remains the standard English body. Bone china production ordinarily involves a two stage firing where the initial "biscuit" is fired without a glaze at 1280°C (2336°F) giving a translucid product and then it is glaze, or glost, fired at a lower temperature under 1080°C (1976°F). buckingham tea saucer is probably manufactured using this method. Soft-paste porcelain Soft-paste porcelain is a type of porcelain and therefore a ceramic material. Its origin dates from the first undertakings by potters from Europe to imitate Chinese porcelain by employing concoctions of china clay and ground-up glass or frit; lime and soapstone were also known to have been employed in some mixtures. As these initial compositions suffered from high pyroplastic collapse, or slumping in the kiln at raised temperature, they were uneconomic to produce. Combinations were later developed based on feldspars, nepheline syenite, kaolin, quartz and other feldspathic rocks. These were technically superior and continue in production today. Hard-paste porcelain Hard-paste porcelain is a hard, dense ceramic that was first made from a formulation of the feldspathic rock petuntse and kaolin fired at extremely high temperature. It was first produced in China around the ninth century. The secret of its manufacture was unknown in Europe until 1709, when Böttger of Meissen, Germany found the formula. Despite attempts to keep it secret, the procedure spread to other German ceramic potteries and in time became used throughout the length and breadth of Europe. Hard-paste porcelain is fired at a range of temperatures to make many different end results. Depending on the firing approach, hard-paste porcelain can be manufactured to resemble stoneware or earthenware. But generally, it is unnecessary to use hard-paste porcelain for these lower temperature ceramics. Hard-paste porcelain can be employed to manufacture porcelain bisque, a hard crystalline product fired at very high temperatures in a pressure controlled environment. This technique gives birth to a translucent bright white ceramic. Unlike other bisque ceramics, porcelain bisque is almost impermeable by water, therefore it becomes unnecessary to glaze the body before decorating. Manufacturers such as Lladro, Hummel and Precious Moments utilize hard-paste porcelain simply for this reason, this could include buckingham tea saucer.
|
