STONEWARE (German-Steinzeug) — Hard material, fired in high temperature kilns generally around 1,200 °C to 1,400 °C . At this temperature, stoneware vitrifies (becomes glass-like). The resulting product is less than 2% porous; therefore, glaze is not mandatory for a stoneware stein. When glaze is used, it must be of a special quality to withstand the high kiln temperature.
Although the major deposits of stoneware clays have been in the Westerwald region, these did not become important until the 1600s. Before that time, and even after the Westerwald area began production, there were several regional stein producers that had their own distinctive styles and decorative techniques. Examples from most of these factories are shown in the Beer Stein Book, their are brief characterizations of the German steins produced by these factories and are listed in Beer Stein history.