Earthenware is the term for pottery that has not been fired to the point of vitrification and is thus porous. Many types of pottery have been made from it from the earliest times. Until the 18th century it was the commonest type of pottery outside the far East.
Definition and treatment
Earthenware is a type of clay that when fired to make pottery is soft and can be scratched with a knife. It is opaque and has an earthy or granular fracture. It is generally easier to shape on the wheel than porcelain. Due to its porosity earthenware must be glazed in order to be watertight.
Earthenware articles may be thick and heavy or as thin as bone china and porcelain, though they are not translucent and are more easily chipped. They are less strong than stoneware.
Earthenware may be biscuit (or "bisque") fired to temperatures between 1000 and 1150 °C (1800 and 2100 °F) and glost-fired (or "glaze-fired") to between 950 to 1,050 °C (1,740 to 1,920 °F), the usual practice in factories and some studio potteries. Some studio potters follow the reverse practice, with a low-temperature bisque firing and a high-temperature glost firing.The firing temperature will be determined by the raw materials used and the desired characteristics of the finished ware.
After firing most earthenware bodies will be colored white, buff or red. For red earthenware, the firing temperature affects the color of the clay body. Lower temperatures produce a typical red terracotta colour; higher temperatures will make the clay brown or even black. Every clay has a temperature at which the body becomes weak and sags. Higher firing temperatures may cause earthenware to bloat.
Types of earthenware
Earthenware comprises "all primitive pottery whatever the colour, all terra-cottas, most building bricks, nearly all European pottery up to the seventeenth century, most of the wares of Egypt, Persia and the near East; Greek, Roman and Mediterranean, and some of the Chinese; and the fine earthenware which forms the greater part of our tableware today." Most pottery from the earliest times onward was earthenware. Pit fired earthenware dates back to as early as 29,000–25,000 BCE. Outside East Asia porcelain was manufactured only from the 18th-century, and then as an expensive luxury.
There are several types of earthenware, including
- Tin-glazed pottery
- Victorian majolica
- Ironstone ware
- "Earthenware" Britannica online
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- Frank and Janet Hamer, The Potter's Dictionary of Materials and Techniques
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- "Petersons": Peterson, Susan, Peterson, Jan, The Craft and Art of Clay: A Complete Potter's Handbook, 2003, Laurence King Publishing, ISBN 1856693546, 9781856693547, google books
- Digital Version of "A Representation of the manufacturing of earthenware" — 1827 text on the manufacture of earthenware
- Short film on pottery making around the world
- Tin-glazed earthenware livery-button, ca 1651, Victoria & Albert museum jewellery collection