Editing Pottery (section)

==Clay bodies and raw materials==
[[File:Clay Mixing for Pottery.jpg|thumb|Preparation of clay for pottery in India]]
{{anchor | Fabric | Paste | Fabric of clay | Paste of clay  | Fabric analysis | Paste analysis | Pottery analysis }}

[[File:Sèvres - Moulin - filtre-presse 024.jpg|thumb|Removing a filter cake of porcelain body from a filter press]]

[[Body (ceramic)|Body]], or clay body, is the material used to form pottery. Thus a potter might prepare, or order from a supplier, such an amount of earthenware body, stoneware body or porcelain body. The compositions of clay bodies varies considerably, and include both prepared and 'as dug'; the former being by far the dominant type for studio and industry. The properties also vary considerably, and include [[Plasticity (physics)|plasticity]] and mechanical strength before firing; the firing temperature needed to mature them; properties after firing, such as permeability,  mechanical strength and colour.

There can be regional variations in the properties of raw materials used for pottery, and these can lead to wares that are unique in character to a locality.

The main ingredient of the body is [[clay]]. Some different types used for pottery include:<ref>Ruth M. Home, "Ceramics for the Potter", Chas. A. Bennett Co., 1952</ref>
* [[Kaolin]], sometimes referred to as [[china clay]], is a key ingredient in [[porcelain]], which was first used in China around the 7th and 8th centuries.<ref>{{Cite web |title=China Clay |url=https://www.thepotteries.org/types/chinaclay.htm |access-date=2024-10-01 |website=www.thepotteries.org}}</ref>
* [[Ball clay]]: An extremely plastic, fine grained [[sedimentary]] clay, which may contain some organic matter.
* [[Fire clay]]: A clay having a slightly lower percentage of [[List of pottery terms#F|fluxes]] than kaolin, but usually quite plastic. It is highly heat resistant form of clay which can be combined with other clays to increase the firing temperature and may be used as an ingredient to make stoneware type bodies.
* Stoneware clay: Suitable for creating stoneware. Has many of the characteristics between fire clay and ball clay, having finer grain, like ball clay but is more heat resistant like fire clays.
* Common red clay and [[shale]] clay have vegetable and ferric oxide impurities which make them useful for bricks, but are generally unsatisfactory for pottery except under special conditions of a particular deposit.<ref>Home, 1952, p. 16</ref>
* [[Bentonite]]: An extremely plastic clay which can be added in small quantities to short clay to increase the plasticity.

It is common for clays and other raw materials to be mixed to produce clay bodies suited to specific purposes. Various [[mineral processing]] techniques are often utilised before mixing the raw materials, with [[comminution]] being effectively universal for non-clay materials.

Examples of non-clay materials include:
* [[Feldspar]], act as [[Ceramic flux|fluxes]] which lower the [[Vitrification#Ceramics|vitrification]] temperature of bodies.
* [[Quartz]], an important role is to attenuate drying shrinkage.[[File:Marcy Ball Mill - Shenandoah-Dives Mill, 135 County Road 2, Silverton, San Juan County, CO HAER CO-91 (sheet 21 of 27) (cropped).png|thumb|right|175px|A section cut-through of ball mill, which are widely used to mill raw materials for pottery]]
* [[Nepheline syenite]], an alternative to feldspar.
* [[Aluminium oxide|Calcined alumina]], can enhance the fired properties of a body.
* Chamotte, also called grog, is fired clay which it is crushed, and sometimes then milled. Helps attenuate drying shrinkage.<ref>''Whitewares: Production, Testing And Quality Control.'' Ryan w. & Radford C. Pergamon Press. 1987</ref>
* [[Bone ash]], produced by the [[calcination]] of animal [[bone]]. A key raw material for bone china.
* [[Frit]], produced made by quenching and breaking up a glass of a specific composition. Can be used at low additions in some bodies, but common uses include as components of a glaze or enamel, or for the body of [[fritware]], when it usually mixed with larger quantities of quartz sand.
* Various others at low levels of addition such as [[Dolomite (mineral)|dolomite]], [[limestone]], [[talc]] and [[wollastonite]].