Stoneware Pottery vs. Earthenware Pottery
| Stoneware | Earthenware | |
| Makeup | Ball clays 0-15%, Quartz, 0-30%, Feldspar and Chamotte 0-15% | Ball Clays ~25%, Kaolin ~28%, Quartz ~32%, Feldspar and Chamotte ~15% |
| Firing Temp (Bisque) | Often around 900 °C (bisque firing optional) | Often between 1000 and 1150 °C |
| Firing Temp (Ghost) | Often between 1180 - 1280 °C | Often between 950 to 1,050 °C |
| Glaze | Primarily Glazed | Glazed or Unglazed (must be glazed to be water tight) |
| Properties | Stronger, denser, impermeable | More fragile, porous |
| Opague | Opague |
Earthenware is a common ceramic material, which is used extensively for pottery tableware and decorative objects. Although body formulations vary between countries and even between individual makers. Earthenware is one of the oldest materials used in pottery. While red earthenware made from red clays is very familiar and recognizable, white and buff colored earthenware clays are also commercially available and commonly used.
The exact temperature will be influenced by the raw materials used and the desired characteristics of the finished ware. The higher firing temperatures are likely to cause earthenware to bloat. After firing, the body is porous and opaque with colours ranging from white to red depending on the raw materials used.
Earthenware may sometimes be as thin as bone china and other porcelains, though it is not translucent and is more easily chipped. It is also less strong, less tough, and more porous than stoneware, but is less expensive and easier to work. Due to its higher porosity, earthenware must usually be glazed in order to be watertight.
Stoneware is a vitreous or semi-vitreous ceramic ware of fine texture made primarily from non-refractory fire clay.[1]
One widely recognized definition is from the Combined Nomenclature of the European Communities, which states:
"Stoneware, which, though dense, impermeable and hard enough to resist scratching by a steel point, differs from porcelain because it is more opaque, and normally only partially vitrified. It may be vitreous or semi-vitreous. It is usually coloured grey or brownish because of impurities in the clay used for its manufacture, and is normally glazed."
Due to its high strength and durabilty stoneware has a wide range of uses, including: hotelware, kitchenware, cookware, garden products, electrical, chemical and laboratory ware.
Water absorption of stoneware products is less than 1%[5][6].
Five categories have been suggested[7]:
Traditional stoneware - a dense and inexpensive body. It is opaque, can be of any colour and breaks with a conchoidal or stony fracture. Traditionally made of fine-grained secondary, plastic clays which can used to shape very large pieces.
Fine stoneware - made from more carefully selected, prepared and blended raw materials. It is used to produce tableware and art ware.
Chemical stoneware - used in the chemical industry, and elsewhere when resistance to chemical attack is needed. Purer raw materials are used than for other stoneware bodies. Ali Baba is a popular name for a large chemical stoneware jars of up to 5000 litres capacity used to store acids[8].
Thermal shock resistant stoneware – has additions of certain materials to enhance the thermal shock resistance of the fired body.
Electrical stoneware - historically has been used for electrical insulators, although has been replaced by electrical porcelain.
Another type, Flintless Stoneware, has also been identified. It is defined in the UK Pottery (Health and Welfare) Special Regulations of 1950 as: "Stoneware, the body of which consists of natural clay to which no flint or quartz or other form of free silica has been added."[9]
