Randy Cullinan, age 14, of Richmond, Va  ,

New plastic materials are being created all the time And lately we  tend to reserve the word plastics for such modern marvels as polyethylene, nylon and styrene  But in a wider sense, the word plastics can be applied to any man‑made substance which can be molded into shape  In this sense, glass is a plastic which has been in use for thousands of years  What’s more, our modern chemists arc adapting glass to new uses and when we look around we find that one of the oldest of plastics is holding its own with some of the very newest  A modern manufacturer may have recipes for making 30,000 to 40,000 different types of glass for different uses 

The windshield on a car is usually laminated, or safety glass  It is a sandwich of thin plastic between two sheets of glass  When shattered by ‑  blows the splinters stay put  The side doors of a car are often tempered glass, five times harder than a window pane  In the kitchen you  may have glass pots for cooking or one of those new glass trays for cooking food  You may have table ware of clear glass, colored glass or opal glass 

All the light bulbs in the home, plus the radio and TV tubes are made of thin glass tubes  The pipes and walls may be insulated with hard  glass foam, light enough to float like cork and easy to shape 

Lenses and spectacles are made of optical glass which is as brilliant a~, a gem  Also in the home, you may have handsome curtains made from fiber glass 

These different types of glass each with its own purpose, are all made from slightly different recipes  The basic ingredients for making glass, however, are the same in all cases  They are sand, lime, and an alkali chemical such as sod 

These three raw materials are cheap and plentiful  But to make glass, they must be heated to thousands of degrees in special furnaces  And almost every recipe has a trace or two of certain ingredients which are not so easy to come by 

When it comes from the furnace glass is a hot, sirupy fluid, In this state it can be molded, blown or pressed into shape  A batch of glass destined to become fiber glass is first made into a host of small round balls, When hard, these little glass marbles are sorted, the flawed ones removed and the perfect ones sent back to be remelted in a furnace  The newly heated glass is pushed through tiny holes and cornea out in fine filaments  As the filaments emerge, they may be blown into short strips by a ,bet of air  Or they may remain fine filaments which are twisted into threads by twos and threes 

The fibers are then coated with a starchy chemical and sent to the textile mill to be woven into fabric called fiber glass  Fabric made from the short fibers looks somewhat like cotton  fabric made from the long threads looks like silk or rayon  In either case, the fiber glass material will have all the good qualities of glass  It will not rust or rot  It will not absorb water and acids cannot stain it  Best of all fire will not burn it