The difference between pottery and porcelain is not that there is glaze or not. Pottery can have glaze, such as the glazed ware of the Han Dynasty (commonly known as the green glaze of the Han Dynasty), the colorful glazed ware of the Tang Dynasty (commonly known as the three colored glazed ware of the Tang Dynasty), etc. Porcelain can also be unglazed, such as white porcelain plain bodied ware. Because of its white and delicate texture, no one will regard it as pottery. In fact, the so-called hard pottery produced in the southern region of China during the Shang and Zhou Dynasties to the Warring States period has reached the level of porcelain, and the sound of percussion is clear and pleasant, which should also belong to the category of primitive porcelain.

       The difference between pottery and porcelain lies in the following two aspects: one is the use of materials; the other is the firing temperature. Pottery can be made of various mineral clays, including porcelain clay. The firing temperature is low, mostly between 700-1000 ℃. The matrix is basically sintered and no longer decomposes with water, but the porosity and water absorption are high. In the observation of the carcass under the microscope, there are few glass phase mullite crystals, in other words, there is no porcelain, and the sound of knocking is dull. The porcelain is made of clay with high alumina content. The firing temperature of porcelain is at least 1100 ℃, and the matrix is basically porcelain like. There are a large number of mullite crystals, with low porosity and water absorption, and the sound of knocking is clear. Western scholars also regard the iron content in the tire as the judging standard of pottery and porcelain. They think that there are more metal impurities such as iron in the tire and the color is darker. The porcelain body has less iron content and white color. I don't think so, the amount of iron does not affect the nature of porcelain, just different aesthetic orientation. Take the five famous kilns in Song Dynasty as an example. Ru, Guan, Ge, Jun and Dingdu used to be imperial porcelain. Among them, the first four are celadon products, and the iron content of the tire exceeds that of the Western porcelain. Only Dingyao belongs to white porcelain, and the iron content of the tire is relatively low.

       Dingyao was only selected as a tool for imperial use in the early Northern Song Dynasty, and was soon eliminated because of its awn.