Slide 1: Mining the Clay

The process of pottery manufacture in Africa begins with the mining and preparation of the clay that the potter will use to form her or his pots. Here, fresh clay is dug from pits with short handled hoes or digging sticks. It is then carried in baskets to the potter's compound where it is left in piles to dry. It is broken up, usually by pounding it in wooden mortars, and any stones or other foreign matter are picked out by hand. Many potters then use a wire mesh sieve to remove large pieces and produce a fine powdered clay. The clay is then placed in large earthenware pots, mixed with water, and left for several days to soak.

Although the mining process appears to be the simplest and most laborious part of pottery making, potters recognize that careful preparation of the clay is essential if their pottery is to survive the rapid heating and cooling of a firing. In addition, it is at this point that the potters believe that they come in closest contact with the spirits which control the earth from which the clay is mined. These spirits can cause the pots to shatter if they are displeased. As a result, most of the religious rituals and the strongest patterns of avoidance for potters are associated with the clay pits and the mining process.

Supplementary Information on Use of Tempers

It is rare that a potter will find clay she considers fit for use just as it comes from the ground. Usually the clay is far too fine and plastic for use. A very plastic clay may be easy to form, but, because of the very fine size of the clay particles, it will absorb large amounts of water and will shrink excessively during drying, causing the pots made from it to crack. To reduce plasticity of the clay body the potter adds temper, or inert matter.

Tempers used in Africa vary widely, but may be generally classed in two categories: organic and inorganic. Organic tempers include finely chopped straw, dried animal dung pounded into a powder, and the chaff left when rice or millet is winnowed to prepare it for cooking. Inorganic tempers include sand, river pebbles, or, most commonly, shards of old pottery which have been reduced to a find powder. Tempers are kneaded into the fresh clay in amounts that vary with the original quality of the material. Generally, the result is a clay body with from thirty to fifty percent inert material.

The tempers that potters add to clay decrease shrinkage of pottery by replacing clay molecules, which contain water and which will shrink during drying and firing, with material which contains no water. By increasing the amount of inert temper to fifty percent of the total mass of the clay body, the shrinkage is decreased by fifty percent. Organic and inorganic tempers work in different ways during the firing. Organic tempers are reduced to carbon, producing tiny voids between the clay particles. African pottery resists cracking during the firing because these voids leave room into which the heated clay particles may expand. Inorganic materials, especially powdered potsherds, which do not contain any water, will not shrink during the firing and thus help to decrease cracking. It should be noted that in adding sufficient temper to prevent cracking the potter produces an extremely stiff clay body that can be modeled freely into thin, high walls without collapsing, and which even he most skilled western potter would find far too stiff for use on a potter's wheel.

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