the VOA Special English Development Report.
Clay is found almost everywhere in the
world. It is formed by the action of wind and water on rocks over thousands of
years. The rocks change in both chemical and physical ways. Chemically,
elements like potassium and aluminum are added and taken away. Physically, the
rocks 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 make containers of all kinds. Potters add water to soften
the clay. This makes it easier to form into shapes by hand or by machine. Then
it is fired in an extremely hot stove. The result is a container with a hard
surface that will last for many years.
many countries, clay was formed from volcanoes. This kind of clay usually
contains many minerals. So the fires to make containers from volcanic clay must
be hotter than those used for non-volcanic clay. The fires may be as hot as one
thousand four hundred degrees Celsius.
It is also important to dry the clay
containers slowly. This means that the highest temperature should not be
reached too fast.
add materials to clay to gain desired results. For example, you can add sand to
prevent tiny breaks or lines from forming in the finished product. But you
should not use sand from the coasts of oceans. Instead, you should use sand
from rivers or from 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 in fields covered with some water. The clay will be found about
one meter below the ground. River banks often also have clay about one meter 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 add enough water to it to make it seem like you are making bread.
Then press it in your hand until it is about the size of an egg. It is probably
clay if it holds together instead of falling apart when you stop pressing.
And that's the VOA Special English
Development Report, written by Gary Garriott. Guides to working with clay and
other materials can be found on the EnterpriseWorks/VITA list of publications.
These publications can be ordered for a charge. The list is at
enterpriseworks.org. Transcripts and MP3 archives of our reports are at