the origin of primitive porcelain
primitive porcelain is developed on the basis of pottery-making technology. In Shang Dynasty ruins in Zhengzhou, Henan Province, many glazed porcelain statues, porcelain jars and so on, as well as the fragments of these objects, were found. The fetal bones were delicate and hard, and the firing temperature was above 1, degrees, with a metallic sound. In 198, a batch of primitive celadon pieces unearthed at Dongxiafeng site in Xia County, Shanxi Province, belonged to the late Longshan culture more than 4, years ago. A large number of celadon porcelain unearthed can be concluded that China supported the invention of porcelain in the middle of Shang Dynasty. At that time, the production of blue glaze porcelain was developed in the middle and lower reaches of the Yangtze River, and the glaze color was mostly bluish yellow, which was fired in the oxidation flame. The celadon glaze porcelain in the Central Plains is mostly turquoise in color and fired in reducing flame. These primitive porcelain are made of kaolin, and the firing temperature is as high as 11~12 degrees. The surface layer is fired into glass enamel which is firmly combined with the matrix at high temperature. The fetal quality is hard and delicate, and the water absorption is very weak, and there is a metallic sound when knocking. Because of the primitive technology, it is called "primitive porcelain" or "primitive celadon". There are statues, beans, cans, urns, bowls and so on.
the difference between porcelain and pottery
a vessel fired with clay is called pottery, and a vessel fired with clay is called porcelain. Ceramics is the general term for pottery, stoneware and porcelain. All objects made of clay with different properties, such as pottery clay and porcelain clay, can be called ceramics after batching, molding, drying and roasting.
definition of pottery
at present, there is no unified opinion on the specific definition of porcelain. Generally speaking, it must meet the following requirements before it can be called porcelain:
First, the tire material of porcelain must be porcelain clay. The composition of porcelain clay is mainly kaolin, and it contains feldspar, quartzite and mullite. Low iron content. After high temperature firing, the tire is white, transparent or translucent, and the water absorption of the carcass is less than 1%, or it does not absorb water.
Secondly, the matrix of porcelain must be baked at 12℃ ~ 13℃ to have the physical properties of porcelain. The firing temperature varies from place to place with different porcelain clay, so the firing shall prevail.
thirdly, the glaze applied on the surface of porcelain must be a glassy glaze that is fired together with porcelain at high temperature.
fourthly, after the porcelain is fired, the matrix must be hard and firm, with fine structure, and it can make a crisp and pleasant metallic sound when knocked.
Third, the initial age of the original porcelain
Production process
The blue glaze wares of Shang Dynasty fully meet the basic requirements for forming porcelain. First, kaolin has been used as a tire. Second, a layer of glassy glaze is applied to the surface. The main components of the glaze are porcelain clay, limestone and plant ash, which are mixed into suspension and coated on the surface of the porcelain blank. When it is baked in the kiln, it melts and forms a glassy substance. Thirdly, the firing temperature has reached about 123℃. So far, the firing temperature of pottery is only 8℃~9℃, and a few of them reach 1℃, while the firing temperature of porcelain is about 123℃. Fourth, pottery has water absorption, while porcelain has no or little water absorption. The water absorption of primitive celadon in Shang Dynasty is only 1%, or lower. Because the content of silicon dioxide (SiO2) in the matrix is above 7% like that of famous kiln porcelain in Tang and Song Dynasties, and the content of aluminum oxide (Al2O3) is above 17%, it is well sintered at a high temperature of about 12℃, which makes the water absorption very weak and reaches the standard of porcelain. Fifth, in terms of physical properties, such as specific gravity, hardness, and the development degree of mullite (also called "mullite") crystals are the same as those of porcelain in the future. There is also a crisp metallic sound when knocking. All these prove that China porcelain has been invented in Shang Dynasty.