Thread is a fine cord. It is used chiefly to join two or more pieces of material or to sew an object to a piece of fabric. Thread is made of such fibers as cotton, flax, nylon, polyester, rayon, silk, or other textile material. Thread has numerous uses. These uses include sewing clothing, mending tears, and attaching buttons.
Most thread is made by spinning many fibers into a single yarn. Several yarns are then twisted tightly together to form thread. Each yarn, called a ply, adds strength and thickness to the thread. Some thread consists of only a single yarn.
Thread is made from three kinds of fibers: (1) plant, (2) animal, and (3) manufactured. Plant and animal fibers are called natural fibers. Almost all natural fibers grow in short lengths known as staple. For example, cotton staple measures from 3/4 inch to 11/2 inches (1.9 to 3.8 centimeters) long. Cotton ranks as the most widely used natural fiber for making thread. Manufactured fibers, such as nylon and polyester, are produced in long, continuous strands called filaments. Silk is the only natural fiber that begins as filament. Silk fibers average from 1,000 to 1,300 yards (914 to 1,189 meters) long.
Most natural and manufactured thread goes through some kind of chemical treatment that improves its quality. One such process, called mercerization, treats cotton thread in a saltlike solution. This chemical treatment strengthens the thread and gives it a silky finish. Almost all of the thread is either bleached or dyed before being packaged.
Making thread from natural fibers.
Natural fibers, such as cotton or flax, are first cleaned. Then they are straightened and further cleaned in a process called carding. The next step, called combing, smooths the staple and removes some of the exceptionally short fibers. The combed fibers pass between sets of powerful rollers that draw many pieces of loosely joined staple into continuous strands of increased strength. The strands are then spun into yarn and wound on bobbins. Several yarns are plied (twisted together) to form thread.
Making thread from manufactured fibers
involves few steps. Filaments need little preliminary processing because they are specifically produced to be made into thread. A single filament can be used as monofilament thread, or many filaments may be twisted together to form multifilament thread. Filaments may also be cut into staple lengths, which are drawn into strands and then spun into yarn and plied. This process produces a softer thread than that made directly from filaments.
One type of manufactured thread, called core thread, combines the qualities of two kinds of fibers. An example of such a thread is a blend of cotton and polyester. This thread is made by combining a core of multifilament polyester with a protective cotton wrap. The resulting strand is plied with two or more similar strands. This process gives the thread the smoothness of cotton and the strength of polyester. Core threads can be sewn on a machine faster than other manufactured thread without heating up and breaking. Core threads are ideal for sewing such textiles as knits, permanent-press fabrics, and fabrics that are made from two or more kinds of fibers.
