The gaiwan, also known as the Sancai bei, Chazhan or Covered bowl, is often used as a substitute teapot. It also can be used as a tea cup. It is normally used for brewing scented tea.
Gaiwan is the preferred method for brewing green and white tea because the gaiwan's porcelain absorbs the heat and does not damage the tea soup. Gaiwans are less suitable for black tea because the large lid allows heat to escape too quickly during the brewing process.