Basin, 1127-1279. Guan ware was the official ware fired at the Southern Song imperial kilns in Hangzhou. Multiple glazing is characteristic of this ware. The total thickness of the glaze can be greater than the clay body that supports it. Here, the thick blue-green glaze is webbed with a wide network of dark brown crackle as well as finer webs of light golden-brown and colourless crackle. The crackle was developed after firing, due to the different rates of expansion and contraction of the body and the glaze. It was consciously exploited to achieve an aesthetic effect and was stained at different stages during the cooling process.