Ceramics of indigenous peoples of the Americas
The clay body is a necessary component of pottery. Clay must be mined and purified in an often laborious process, and certain tribes have ceremonial protocols to gathering clay. Different tribes have different processes for processing clay, which can include drying in the sun, soaking in water for days, and repeatedly running through a screen or sieve. Acoma and other Pueblo pottery traditionally pound dry clay into a powder and then remove impurities by hand, then running the dry powder through a screen, mixing it with a dry temper, and then mixing water to create a plastic paste. In preparing the clay, potters spend hours wedging it to remove air pockets and humidity that could easily cause it to explode during firing. The clay then needs to "cure" over time.
Pottery
There are several materials that are referred to as clay. The properties which make them different include:
Plasticity, the malleability of the body; the extent to which they will absorb water after firing; and shrinkage, the extent of reduction in size of a body as water is removed. Different clay bodies also differ in the way in which they respond when fired in the kiln. A clay body can be decorated before or after firing. Prior to some shaping processes, clay must be prepared. Each of these different clays are composed of different types and amounts of minerals that determine the characteristics of resulting pottery. There can be regional variations in the properties of raw materials used for the production of pottery, and this can lead to wares that are unique in character to a locality. It is common for clays and other materials to be mixed to produce clay bodies suited to specific purposes. A common component of clay bodies is the mineral kaolinite. Other mineral compounds in the clay may act as fluxes which lower the vitrification temperature of bodies. Following is a list of different types of clay used for pottery.