Antique Salt Glaze Earthenware Jug. Traditional shape with an "M" stamped into the side near the bottom directly below the handle. Scribbled blue lines adorn the front, almost like an abstract image of a bird standing on one leg with wings outstretched. No stopper in the opening. 

Size: 8 x 8 x 13 1/2 in. 

Salt-glaze or salt glaze pottery is pottery, usually stoneware, with a ceramic glaze of glossy, translucent and slightly orange-peel-like texture which was formed by throwing common salt into the kiln during the higher temperature part of the firing process. Sodium from the salt reacts with silica in the clay body to form a glassy coating of sodium silicate. The glaze may be colorless or may be colored various shades of brown (from iron oxide), blue (from cobalt oxide), or purple (from manganese oxide). The earliest known production of salt glazed stoneware was in the Rhineland of Germany around 1400, and it was effectively the only significant innovation in pottery of the late European Middle Ages. Initially, the process was used on earthenware, but by the 15th Century small pottery towns of the Westerwald, including Höhr-Grenzhausen, Siegburg, Köln, and Raeren in Flanders were producing a salt-glazed stoneware, with the Bartmann jug a typical product. In the 17th Century, salt glaze gained popularity in England as well as in Colonial America and Canada. During the 20th Century, the technique was promoted for studio pottery use by Bernard Leach. In the 1950s it was introduced into Japanese craft pottery through Leach’s association with Shōji Hamada. Don Reitz introduced salt glazing into the curriculum at Alfred University in New York in 1959, and it subsequently spread to other American universities with ceramic art programs. However, beyond the studio movement, the process is now effectively obsolete, due to concerns of significant amounts of air pollution resulting from the process. It was last used on any large scale for the production of salt-glazed sewer-pipes, with some reports of it still being used for this purpose in India.