What is pottery?

When designing pottery direction, according to usage requirement, a large number of raw materials which can produce gas during baking process are added but fusing agent material is less relatively. In this way, after being baked, a lot of hollow space occurs owing to air removing and there isn’t much glass phase to fill in them so that many air holes form accordingly, especially the opening air holes which communicate with atmosphere. Consequently, it owns higher water absorption and this kind of ceramics whose water absorption (E) is more than 10% comes to be known as pottery.

Owing to multi-hole base structure of pottery, it is poor in exquisite, large in water absorption and hygroscopic expansion, easily causing late fissuration. The frost resistance is also required on ceramic products of construction sanitary ceramics, mainly the glaze internal wall brick. As it is the wall brick, indoor usage requires not so high on mechanical strength so that frost thawing problem doesn’t exist. With advancement of science and technology, not only the water absorption of glaze brick reduces gradually but also its hygroscopic expansion decreases. With further enhancement of its performance, it is still the preferred variety among indoor wall decorative ceramic material. Construction colored glaze product, owing to big piece, thick body and plastic making, owns larger water absorption, considered to be pottery as well. The colored glaze products are seldom used outdoor in cold regions.