This teapot is made from salt-glazed stoneware, a type of ceramic that was made in London from the 1680s, before spreading to the Staffordshire factories in the 1710s. The glaze is created when salt is added to the kiln at high temperatures. The sodium that is released combines with the silica found in the clay and forms a glossy glaze of sodium silicate. In Staffordshire, the production of salt-glazed stoneware flourished in the 18th century before it was superseded by the invention of creamware, a type of earthenware, from about 1780. This teapot was made in Staffordshire around 1755, and the unusual lozenge shape was created using the slip-casting process, in which liquid clay is poured into plaster moulds to create the form. The development of this technique during the 1740s helped to revolutionise the mass production of ceramic wares. Many salt-glazed teapots of this shape survive today.