StonewareStoneware is a hard, strong, and vitrified ware, usually fired above 1200 C (2192 F), which allows the body and glaze to mature at the same time and form an integrated body glaze layer. During firing, the organic matter found in clay is burned away, the color changes, and a layer of glass is fused onto the surface. The quality of the glaze owes much to the establishment of this layer, and it is therefore the glaze quality that determines a ware's