Mary Lauber, age 13, of Tacoma, Wash., for her question:
HOW IS RAYON MADE?
Rayon is a manufactured fabric that is produced from wood pulp or cotton linters. Linters are the short cotton fibers remaining on cottonseeds after ginning. Rayon is widely used to make knit and woven textiles for clothing, upholstery, draperies and decorating fabrics.
Rayon is made from the linters or pulp after this cellulose fiber is reduced to a thick liquid with the addition of various chemicals. In the process, the liquid is then forced through extremely small openings in devices called spinnerets to form filaments, or tiny threads.
There are three chief methods for making rayon: the viscose process, the coprammonium process and the acetate process.
The viscose process starts with the soaking of sheets of white pulp in a solution of sodium hydroxide. After the soaked sheets of cellulose are removed, they are put through presses that squeeze out the excess solution.
Next the sheets are put through shredding machines where they are made into fine pieces called crumbs. The crumbs of cellulose are aged at high temperatures for about a day and then they are treated with carbon disulfide. The addition of a weak solution of sodium hydroxide turns the mixture to a thick molasseslike solution which ripens for four or five days.
When the solution has ripened, it is pumped to spinning machines and forced through spinnerets to form filaments.
The cuprammonium process dissolves cotton cellulose in a copper ammonia solution. The spinning process produces yarns of ultrafine denier, or weight.
The acetate process changes the properties of cellulose with the addition of sulfuric acid.
Viscose and cuprammonium rayons dye easily. Both lose their strength when wet but regain their original strength when dry. Acetate has special qualities such as fineness and texture that make it desirable. It can also be treated so the material has permanent pleats.
A French industralist named Hilaire Chardonnet patented the first practical synthetic fiber in 1884. He called it "artificial silk."
Chardonnet's fiber was first manufactured in the United States in 1910. In 1924 it was renamed "rayon." The word was a composite: the "ray" indicated the sheen of the new fiber and the "on" showed that it was a cottonlike fiber.
Chardonnet's studies of silkworms and of the structure of natural silk fibers helped him develop synthetic fibers. He studied under Louis Pasteur when Pasteur was carrying on research work on silk and silkworms.
Flannel, a woven fabric usually made of soft woollen or worsted wool fibers, may also be made of rayon, and it often is.
Often synthetic fibers have qualities superior to those in natural fibers. Often they are stronger, more elastic and more resistant to abrasion, heat and rotting than natural fibers.