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Mesa Verde National Park

This is 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.

In 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.

You can 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 available at enterpriseworks.org. Transcripts, MP3 and archives of our reports are at voaspecialenglish.com. I’m Chris Cruise.

This is the VOA Special English Development Report.

Before refrigerators were invented, the next best thing was an ice box. But another way to keep food fresh is to use an evaporative cooler. A common design is a tall box with several shelves inside to hold the food. The shelves are pieces of metal with many small holes through them. The sides of the box are covered with pieces of thick cloth. 

Containers of water are placed at the top and bottom of the cooler. The ends of each piece of cloth lie in the water so the cloth stays wet.

The cooler is put outdoors, but not in the sun. Air will pass through the wet cloth. The inside of the box will stay several degrees cooler than the outside air temperature. And this may be cool enough to keep foods fresh, at least for a short time.

Some foods can make you sick if they are stored in conditions that are not cold enough to prevent the growth of harmful organisms. Freezing can keep some foods in good condition for months after the growing season. Yet foods can be damaged if they are kept too cold.

The British development group Practical Action says the best way to prepare foods for storage is at harvest time while still in the field.

Use a sharp knife and place the harvested items on a clean surface or directly into storage containers. Do not put them on the ground.

Use clean water to remove dirt, and keep the water clean. Usually it is better not to remove outer leaves from fruits and vegetables before storage. Without the leaves, food can become dry.

Fruits and vegetables must be cool from field heat before they are put into storage. But cooling them in water can spread fungus throughout the food. A better idea is to harvest foods either early or late in the day, then leave them to cool naturally.

Some fruits and vegetables must be stored at zero to four degrees Celsius. Any colder, and they might be damaged. Some foods need to be stored at four to eight degrees, and some need to be stored above eight degrees for best results.

Wet the fruits and vegetables so they do not become too dry. The best time to do this is before storage. Cover the items in plastic once they reach the right “critical temperature” for storage. Most fruits and vegetables need the relative humidity in storage to be kept between eighty-five and ninety-five percent.

Finally, leave space between the food containers and the walls of the cold storage area so air can flow. Keep the space clean. And try not to open the doors too often.

And that’s the VOA Special English Development Report. I’m Steve Ember.