<human>:  What is the history of raku pottery?
<bot>: Raku pottery is a traditional form of pottery developed in 16th century Japan. The technique originated in the more rustic celebration of tea ceremonies, in contrast to other types of pottery created for more formal settings. It was popularized by the Japanese master potter, Chōjirō, a student of the famous tea master Sen no Rikyū. The technique was then passed down in the Imperial Household Agency and to the recognized Raku family. The process of Raku focuses on creating ware in a very quick firing process that gives an almost "flash fire" look to the pieces. The ware is then rapidly cooled by removing it from the kiln while still extremely hot and placing it in combustible materials or water. This creates a signature crackle pattern on the surface of the material, where clay pieces have pulled away from each other. The contemporary pieces are usually glazed with earthy, muted tones and are often used for the traditional Japanese tea ceremony.