Mary Jo Bailey, age 13, of Glendale, Ariz., for her question:

JUST WHAT IS POLYESTER?

Polyester is the general name for any of a group of widely used synthetic products. Polyesters are strong, tough materials that are manufactured in a variety of colors, shapes and sizes. Polyesters are manufactured in three basic forms: fibers, films and plastics.

Polyesters are made from chemical substances found in air, coal, petroleum and water.

Polyester fibers are used to make fabrics that are easy to care for and fabrics that resist fading, wrinkling and mildew. They are used in carpets, permanent press clothing, underwear and upholstery. Polyester fabrics are also used as the tough cord fabric in auto tires.

Polyester film has a variety of uses, including in magnetic tapes for use in computers and tape recorders. It is also used as insulation for electric wires or as thin, airtight seals on packages.

Polyester plastics are used chiefly in the production of reinforced plastics, such as airplane windows, boats, automobiles, luggage, machine parts and other products.

Polyester starts as a synthetic compound called resin.