Yixing teapots are ornamental clay pots steeped in Chinese culture. These prized Chinese pots are made from Yixing clay, a special type of clay from the region near the city of Yixing in Jiangsu province, China. The clay absorbs a tiny amount of tea during brewing. After prolonged use, the pot will develop a coating that retains the flavor and color of the tea. Over time, the pot will become so saturated with the flavors of the tea, that one need only use hot water to make a brew.
Yixing teapots are meant for use with green, white, black and oolong teas, as well as aged pǔ’ěr tea. Only one type of tea should be used per Yixing pot, as using multiple types of teas will muddle the flavor. It is a common practice to posses multiple Yixing pots for different types of tea.
Due to its unique nature, a Yixing pot requires a little special care. Before using a Yixing teapot, it is essential to rinse it in boiling water to remove bits of clay. The pot should also be rinsed with boiling water after each use and allowed to air dry. Soap or detergents should not be used to clean Yixing teapots, as the chemicals will be absorbed into the clay. Also, the tea should not be left damp for prolonged periods, as it will develop mold.
The term "yixing clay" is often used as an umbrella term to describe several distinct types of clay used to make stoneware:
Zisha is a mixture of kaolin, quartz and mica, with a high content of iron oxide. It is mined principally at Huanglongshan and Zhaozhuangshan and has a somewhat sandy texture. The process of preparing the clay is lengthy and was traditionally regarded as a trade secret. Typical firing temperature is between 1100C - 1200C in an oxidizing atmosphere.
The raw materials for yixing clay are buried deep underground, sometimes under heavy sedimentary rock formations. When excavated, it is usually located within stratified layers of other clays. The seam of yixing zisha can be as thick as a several decimeters, up to a meter. Yixing clays consist of fine iron-containing silt, with mica, kaolinite and varying quantities of quartz and iron ores as its main mineral constituents.
Processing of raw zisha yixing clay involves removing the clay from the underlying strata, drying it under the sun in open stalls, and then pulverizing the dried clay pieces into fine particles. The clay powder then undergoes air screening to isolate clay particles of the finest grit size. The screened clay is then mixed with water in a cement mixer to a thick paste, piled into heaps, and vacuum processed to remove air bubbles, in addition to some moisture from the clay mixture. The quality and quantity of water in yixing clay is critical in that it determines the quality of the stoneware products produced. After this processing, the resulting clay is then ready to be used.
The appearance of yixing products, such as its colour or texture, can be enriched and altered through the addition of various metal oxides into the yixing clay, through the manipulation of firing temperatures, and also from regulating the kiln atmosphere (oxidative versus reductive).
Archaeological excavations reveal that as early as the Song Dynasty (10th century) potters near Yixing were using local "zisha" clay to make utensils that could have functioned as teapots. The late Ming Dynasty author Zhou Gaoqi stated that during the reign of the Zhengde Emperor (1502–1521) a monk from Jinsha Temple (Golden Sand Temple) in Yixing handcrafted a fine quality teapot from local clay. Such fine quality teapots soon became popular with the scholarly class, and the fame of Yixing teapots began to spread.