Artificial porcelain, made in Europe before the discovery of kaolin, one of the ingredients necessary for true, or hard-paste, porcelain. It was manufactured from white clays, mixed with ground glass to give it translucency. It was first produced at the Medici factory in Florence between 1575 and 1587 and then in France in the early 18th century. The Sèvres factory made only soft-paste for its first thirty years and it was the main type of porcelain produced in England in the 18th century.