The technique of salt glazing dates to the end of the seventeenth century in England. It involved throwing common salt into the kiln when it had reached its maximum temperature of about 1,000° C (1,832° F). When heated, the salt vaporized and split into its component elements: chlorine, which passed out of the kiln chimney, and sodium, which combined with the silicates in the body of the ware to form a thin, glass-like glaze. In order to produce a successful salt glaze, the salt was dampened with water and applied several times in the course of firing. Because of the vapors produced, salt glazing could be harmful to the potter.