By the 11th century, kilns in China routinely produced white procelain by combining kaolin clay and ground porcelain stone fired at around 2400 F. In response, 12th-century kilns in Syria and Iran popularized a different ceramic. Fritware, or stonepaste, was made from carefully prepared stone combined with ground glass, called frit, and a small amount of clay. The mixture was then fired at around 1830 F. Frit was made by pouring molten glass into water, which shattered the glass. The tiny pieces of glass, when combined with the stone and clay, caused the material to fuse. During the 13th century, kilns in Iran began painting blue-and-black decoration on their fritware before it was covered with a transparent glaze and fired.