Non-refractory fire clay may be another key raw material.
Fire clays are generally considered refractory, because they withstand very high temperatures before melting or crumbling.
New England and Ohio followed suit in the latter decades of the 1800s. By definition, stoneware is a type of clay with a waterproof rating of less than 2%. Colors, density, and texture of stoneware vary greatly.
Stoneware has a coarse texture and is often decorated with a brown or gray salt glaze with blue decorations.
Vibrant blue decorations, achieved by the use of a cobalt oxide slip, are considered a trademark of salt glaze ceramics.
Watch me show you how to identify a stoneware crock worth ,000.If you are unsure that your stoneware is Red Wing, you can contact the stoneware experts at the Red Wing Collectors Society by using the “Ask the Experts” link and they will help verify the maker and provide an estimated value.The salt glaze is formed by throwing salt into the kiln during the higher temperature part of the firing process.Refractory fire clays have a high concentration of kaolinite, with lesser amounts of mica and quartz.Non-refractory fire clays, however, have larger amounts of mica and feldspar.Salt glaze is the tell tale sign of a piece of antique stoneware and it is recognizable by the salty or pebbled surface on a stoneware crock.The use of salt glaze results in a rough texture on the surface of a stoneware crock.The use of stoneware articles included storage vessels for a wide range of consumables, such as water, soda, beer, meat, grain, jelly and pickled vegetables.By the 1770s, the production of salt-glazed stoneware production had spread to many centers throughout the United States, most notably Manhattan, New York.Stoneware is a coarse, glazed, and fired potter's ceramic that is used to make crocks, jugs, bowls, etc. ff3=4&toolid=10044&campid=5336649018&customid=stoneware&lgeo=1&mpre= It is often decorated with cobalt blue decorations.