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.
Llangolman
The springs emerge in boggy land at the base of the gravel banks, where deposits of blue boulder clay, known by the natives as "indiarubber clay", can also be found. Clay pits close to the farmhouses of Llangolman Farm (still visible) and Llyn are evidence that the clay was once extracted on a significant scale. The study by Jehu mentions that the clay pit at Llyn was down to a depth of 15 to 20 feet, and ladders were required to get in and out. His report goes on to state that the clay is bluish in color and very tough (hence the nickname indiarubber clay). The clay covers the valley bottom from Llyn to Llangolman Farm at a level of over 400 ft.