Salt glaze

1600 • Illustration — Salt glazed containers Except for its use by a few studio potters, the process is obsolete. Before its demise, in the face of environmental clean air restrictions, it was last used in the production of salt-glazed sewer-pipes. The only commercial pottery in the UK currently licensed to produce salt glaze pottery is Errington Reay at Bardon Mill in Northumberland which was founded in 1878.

• Illustration — Salt glaze jug, 19th century The earliest known production of salt glazed stoneware was in the Rhineland of Germany around 1400; it was effectively the only significant innovation in pottery of the European Middle Ages. Initially, the process was used on earthenware. 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. Westerwald Pottery was characterized by stamped medallions and the use of a cobalt oxide based colorant for decoration. Production of salt glaze pottery in Westerwald ceased because of environmental considerations in 1983. In the UK during the 17th century and 18th century, high quality salt-glazed stoneware was produced in Derbyshire, Nottinghamshire, London and Staffordshire. Salt glazed pottery was also popular in North America from the early 17th century until the early 19th century, indeed it was the dominant domestic pottery there during the 19th century. Whilst its manufacture in America increased from the earliest dated production, the 1720s in Yorktown, significant amounts were imported from Britain until around the mid-19th century. 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. Due to concerns of significant amount of air pollution resulting from the process environmental clean air restrictions led to the demise of widespread use of salt glazing. It was last used on any large scale for the production of salt-glazed sewer-pipes, and other than limited use by some studio potters the process is obsolete, although there are reports of it still being used for sewer-pipes in India.

Experiments in stoneware production began in England during the second part of the 17th century. The earliest evidence has been dated 1650–1700 at the site of a kiln at Woolwich Ferry, London. The similarity of the ware to German products of a similar era has led it to be attributed to immigrant potters. A significant English manufacturer of salt glaze pottery was John Dwight at the Fulham Pottery, which he founded in 1672. In a related patent application, which was granted in 1671, he also claimed to have "discovered the mystery of transparent earthenware commonly knowne by the name of porcelaine or China and Persian ware." • Illustration — Salt glazed jug by Doulton. England, 1875 By the 1800s Lambeth in London had become a centre for the production of salt glaze stoneware, and most especially after the establishment of Doulton and Watts Pottery, which later became Royal Doulton. The company was founded in 1815 when John Doulton formed a partnership with the owner, Martha Jones and foreman, John Watts, of an existing pottery in Lambeth. Initially the factory specialised in utilitarian salt glazed stoneware, similar to that produced by the Fulham factories. During the 1830s and 1840s, considerable amounts of salt-glazed sewer-pipes were produced by Doultons following Sir Edwin Chadwick's advocacy of improved sanitary conditions. Doultons were also one of the earliest manufacturers of electrical insulators, initially using salt glaze stoneware and for the electrical telegraph systems. Also, from about 1830, they started production of salt glaze stoneware vessels, which were valued for their acid resistance, for the emerging chemical industries. From the 1850s Doulton & Co.'s decorative stoneware, that was produced in association with the nearby Lambeth School of Art, enjoyed significant success at various international exhibitions, including at The Great Exhibition in 1851, Philadelphia Exhibition in 1876, and also at Chicago in 1893. Their salt glaze decorative products became known as 'Doulton Ware'. By 1890 their decorative stoneware were so successful that 350 designers and artists were employed at the Lambeth factory, including the famous George Tinworth. Doulton’s Lambeth factory closed in 1956, due largely to new clean air regulations that prohibited the production of salt glaze in the urban environment. Production, but not of salt glazing, was transferred to their factory in Burslem which had been established in 1877. Several other stoneware potteries also operated in Lambeth between the mid-18th & 19th centuries, including James Stiff and Sons and Stephen Green's Imperial pottery. The former having started his pottery career at Doulton in 1830, before opening his own factory in 1843. • Illustration — C19th Vitrious Stone Bottle", Gerrards Bridge Pottery, St Helens, Lancashire for porter/beer.

• Illustration — Salt-glazed pipe vent, New Zealand, 1910–1936 One of the first potteries in the US was on Bean Hill in Norwich, Connecticut. They manufactured yellow-brown, salt-glazed earthenware. According to a rather dubious local legend, their salt glaze technique was discovered in about 1680 by a servant. There was an earthenware vessel on the fire with brine in it to cure salt pork. While the servant was away the brine boiled over, the pot became red hot, and the sides were found to be glazed. A local potter utilized the discovery and salt glaze became established. The earliest known production of salt glaze pottery in Australia has been dated to 1850–1883.