Dating japanese pottery
The terms soft and hard porcelain refer to the soft firing (about 2,200 °F, or 1,200 °C) necessary for the first, and the hard firing (about 2,650 °F, or 1,450 °C) necessary for the second.By coincidence they apply also to the physical properties of the two substances: for example, soft porcelain can be cut with a file, whereas hard porcelain cannot.
Raw clay consists primarily of true clay particles and undecomposed feldspar mixed with other components of the igneous rocks from which it was derived, usually appreciable quantities of quartz and small quantities of mica, iron oxides, and other substances.Tin-glazed earthenware is usually called majolica, faience, or Kamakura period).The first production of stoneware in Europe was in 16th-century Germany.This is sometimes used as a test for the nature of the body.In the course of experiments in England during the 18th century, a type of soft porcelain was made in which bone ash (a calcium phosphate made by roasting the bones of cattle and grinding them to a fine powder) was added to the ground glass.The Chinese, on the other hand, define porcelain as any ceramic material that will give a ringing tone when tapped.
None of these definitions is completely satisfactory; for instance, some thinly potted stonewares are slightly translucent if they have been fired at a high temperature, whereas some heavily potted porcelains are opaque.
When tea was first imported to Europe from China in the 17th century, each chest was accompanied by a red stoneware pot made at the Yixing kilns in Jiangsu province.
This ware was copied in petuntse (a feldspathic rock also called china stone), the latter being ground to powder and mixed with the clay.
Pottery, one of the oldest and most widespread of the decorative arts, consisting of objects made of clay and hardened with heat.
The objects made are commonly useful ones, such as vessels for holding liquids or plates or bowls from which food can be served.
During the firing, which took place at a temperature of about 2,650 °F (1,450 °C), the petuntse vitrified, while the refractory clay ensured that the vessel retained its shape.