This is the VOA Special English Development Report.
Clay is found almost everywhere in the world. It is formed by theaction of wind and water on rocks over thousands of years. The rockschange in both chemical and physical ways. Chemically, elements likepotassium and aluminum are added and taken away. Physically, therocks break down into smaller and smaller pieces. After a long time,some of the rock changes to clay.
Clay is important because it is used around the world to makecontainers of all kinds. Potters add water to soften the clay. Thismakes it easier to form into shapes by hand or by machine. Then itis fired in an extremely hot stove. The result is a container with ahard surface that will last for many years.
In many countries, clay was formed from volcanoes. This kind ofclay usually contains many minerals. So the fires to make containersfrom volcanic clay must be hotter than those used for non-volcanicclay. The fires may be as hot as one-thousand-four-hundred degreesCelsius.
It is also important to dry the clay containers slowly. Thismeans that the highest temperature should not be reached too fast.
You can add materials to clay to gain desired results. Forexample, you can add sand to prevent tiny breaks or lines fromforming in the finished product. But you should not use sand fromthe coasts of oceans. Instead, you should use sand from rivers orfrom other areas of land that are not near the sea.
You can usually find good clay in low areas of islands or land,especially if volcanoes helped form the land. Clay often exists infields covered with some water. The clay will be found about onemeter below the ground. River banks often also have clay about onemeter or less under the surface.
You can recognize clay because it is very shiny when it is wet.You can also perform a test. Take some of the material and addenough water to it to make it seem like you are making bread. Thenpress it in your hand until it is about the size of an egg. It isprobably clay if it holds together instead of falling apart when youstop pressing.
You can learn more about working with clay from Volunteers inTechnical Assistance. VITA’s Web site is www.vita.org.
This VOA Special English Development Report was written by GaryGarriott.
[Rebroadcast from August 30, 1999]