Bill Green, age 14, of Carson City, Nev., for his question:
WHAT IS USED TO MAKE FIBERGLASS?
Fiberglass is sometimes called "fibrous glass." It is glass in the form of fine threads or fibers. Fiberglass is made from the sand and other raw materials used to make ordinary glass. Sand (silicon dioxide), is mixed with lime (calcium carbonate) and sodium carbonate.
The fibers in fiberglass may be many times finer than human hair and may look and feel like silk. The flexible glass fibers are stronger than steel and will not burn, rot, stretch or fade.
Often fiberglass is woven into cloth to make such products as curtains and tablecloths. The cloth does not change its properties when dried. It will not wrinkle or soil easily and needs no ironing after washing.
Fiberglass textiles are also used for electrical insulation. In bulk form, fiberglass is used for air filters and for heat and sound insulation. Air trapped between the fibers makes it a good insulator.
Fiberglass reinforced plastics are extremely strong and light in weight. They can be molded, shaped, twisted and poured for a great many different uses.
Strands of fiberglass may be made in different ways. In one method, the raw materials are heated and formed into small glass marbles so workers can examine them for impurities. The marbles are then melted in special electric furnaces.
The melted glass runs down through tiny holes at the bottom of the furnace. A spinning drum catches the fibers of hot glass and winds them on bobbins, like threads on spools. Because the drum revolves much faster than the glass flows, tension pulls the fibers and draws them out into still finer strands.
The drum can pull two miles of fibers in a minute. Up to 95 miles of fiber can be drawn from one marble five eights of an inch in diameter.
In another method of making fiberglass, the marble making steps are omitted. This method is called direct melt process.
Bulk fiberglass, or fiberglass wool, is made somewhat differently. Sand and other raw materials are melted in a furnace. The melted glass then flows from tiny holes in the furnace. Then high pressure jets of steam catch it and draw it into fine fibers from 8 to 15 inches long. The fibers are gathered on a conveyor belt in the form of a white wool like mass.
Fiberglass has a long history. The Egyptians used coarse glass fibers for decorative purposes before the time of Christ.
Edward Drummond Libbey, an American glass manufacturer, exhibited a dress made of fiberglass and silk at the Columbian Exposition in Chicago in 1893.
Experiments conducted from 1931 to 1939 by the Owens Illinois Glass Company, now called Owens Illinois, Inc., and the Corning Glass Works developed practical methods of making fiberglass commercially.