Clay

Clay is a type of fine grained natural soil material. Clay is able to be worked into a desired shape when wet, and becomes hard and brittle when dried or fired, retaining its previous shape.

Uses

Ceramics

Clay can be shaped when wet and then fired to create clay ceramics, including bricks which can be used for construction, and pottery which includes clay vessels, dishware, pipes, and other wares.

Construction

In addition to clay bricks, clay can be used directly in buildings, such as in the daub used in wattle and daub construction, or in the walls of a Bloomery Furnace.

Writing

Clay tablets are the earliest known medium for writing, used in Sumeria and Greece as early as 3000 BCE. Symbols can be inscribed into wet clay using a stylus, and the clay can either be remolded to record a new set of symbols or fired to make the record more permanent.

Natural Sources

Clay can be gathered from riverbanks and dry riverbeds or lakebeds in almost any part of the world. Wet clay is slippery even if it is unprocessed, unlike other kinds of soil or sand. A sample of clay can be tested by wetting it to a workable consistency and seeing if it breaks when rolled out or coiled into shape. A good sample of clay will be easy to work and resistant to breaking.

Processing

Before using clay, impurities such as stones and plant matter should be removed. This can be done by picking the impurities out while the clay is dry, by sifting the clay through a sieve, or by filtering clay particles suspended in water by passing them through a cloth. If clay is intended to be used for ceramics, it can be tempered with sand or with ground up bits of broken previously fired ceramics. This will improve the chance that the clay fires successfully.

This article uses material from the Wikipedia article clay, which is released under the Creative Commons Attribution-ShareAlike 3.0 Unported License (view authors).