Black-glazed ceramics had humble origins and most were generally inexpensive utilitarian wares used by the middle class. From the tenth through thirteenth centuries, however, a high demand for vessels with thick, brownish-black glazes spread throughout most levels of Chinese society. It is estimated that, during Sung (960-1279), more than a third of all kilns produced some form of brownish-black glazed ware and frequently imitated the black wares of each other in highly competitive markets.

Tenmoku (also spelled "temmoku" and "temoku") is a dark glaze with a surface that resembles oil spotting. It is comprised of feldspar, limestone, and iron oxide. The more quickly a piece is cooled, the blacker the glaze will be. Tenmoku takes its name from the (Mandarin: tiān mù; Japanese: ten moku; English: "Heaven's Eye") mountain temple in China where iron-glazed bowls were used for tea.

Tenmoku's are known for their variability. During their heating and cooling, several factors influence the formation of iron crystals within the glaze. A long firing process and a claybody which is also heavily colored with iron increase the opportunity for iron from the clay to be drawn into the glaze. While the glaze is molten, iron can migrate within the glaze to form surface crystals, as in the "oil spot" glaze, or remain in solution deeper within the glaze for a rich glossy color. Tenmoku glazes can range in color from dark plum (persimmon), to yellow, to brown, to black.