Cotton Fibers – the king of fibers

When we hear the word “cotton”, pleasant memories and mental images of soft sheets and comfortable garments run through our heads. From the earliest historical times, cotton has had a significant role in many of the world’s human cultures. Even the Egyptian pharaohs had cotton. Our modern-day word for “cotton” is derived from the old Arabic word “al qatn”.

Unknown to most people is the true miracle of the cotton fiber, especially its origin and biological characteristics. Each cotton fiber is a single plant hair. Each hair is only one single cell that develops from the surface of cottonseed with each seed producing from 10,000 to 20,000 fibers. The presence of hairs on plant seeds is not an unusual event, but the characteristics of the seed hairs on the wild plants that became cotton are unique. They alone, of the world’s plant hairs, have the combination of length, strength, and three-dimensional structural characteristics in the dried state that enable them to be spun into yarn or thread.

Cotton is the most important natural textile fiber, as well as cellulosic textile fiber, in the world, used to produce apparel, home furnishings, and industrial products. Worldwide about 40% of the fiber consumed in 2004 was cotton.

Cotton fibers are seed hairs from plants of the order Malvales, family Malvaceae, tribe Gossypieae, and genus Gossypium. Botanically, there are four principal domesticated species of cotton of commercial importance: hirsutum, barbadense, aboreum, and herbaceum. Thirty-three species are currently recognized; however, all but these four are wild shrubs of no commercial value. Each one of the commercially important species contains many different varieties developed through breeding programs to produce cotton with continually improving properties (e.g., faster maturing, increased yields, and improved insect and disease resistance) and fibers with greater length, strength, and uniformity.

The cotton fibers used in textile commerce are the dried cell walls of formerly living cells. Botanically, cotton fibers are trichomes or seed coat hairs that differentiate from epidermal cells of the developing cottonseed. The cotton flower blooms only for one day and quickly becomes senescent thereafter.  On the day of full bloom, or anthesis, the flower petals are pure white in most hirsutum varieties. By the day after anthesis, the petals turn bright pink in color, and, usually by the second day after anthesis, the petals fall off the developing carpel (boll).

Each cotton fiber is composed of concentric layers and a hollow central core is known as the lumen. The outermost layer, known as the cuticle, is a thin layer of fats, proteins, and waxes. Beneath the cuticle is the primary wall, composed mainly of cellulose in which fibrils are arranged in a criss-cross pattern. Further towards the center is the secondary wall composed of cellulose, which consists of the bulk of the fiber.

Cotton today is the most used textile fiber in the world. Its current market share is 56 percent for all fibers used for apparel and home furnishings and sold in the U.S. Another contribution is attributed to nonwoven textiles and personal care items. The earliest evidence of using cotton is from India and the date assigned to this fabric is 3000 B.C. There were also excavations of cotton fabrics of comparable age in Southern America. Cotton cultivation first spread from India to Egypt, China, and the South Pacific.

Cotton is a soft, staple fiber that grows in a form known as a boll around the seeds of the cotton plant, a shrub native to tropical and subtropical regions around the world, including the Americas, India, and Africa. The fiber most often is spun into yarn or thread and used to make a soft, breathable textile, which is the most widely used natural-fiber cloth in clothing today. The English name derives from the Arabic (al) qutn قُطْن , which began to be used circa 1400.

Each cotton fiber is composed of concentric layers. The cuticle layer on the fiber itself is separable from the fiber and consists of wax and pectin materials.

Properties of Cotton

Cotton is a natural fiber that is grown in countries around the world. It is a crop that requires adequate moisture and heat to mature and produce quality fibers. Cotton growing tends to be in warmer climates. Cotton is a true commodity in the world markets and supply and demands truly affect the prices of raw cotton.

Cotton fibers are mainly made up of cellulose. Cellulose does not form unless temperatures are over 70 °F (21 °C). The cotton fibers are attached to the seeds inside the boll of the plant. There are usually six or seven seeds in a boll and up to 20,000 fibers attached to each seed. The length of these fibers (also called staples) is the main determining factor in the quality of the cotton. In general, the longer the staple grows the higher the quality of the cotton. Staple lengths are divided into short, medium, and long (and extra-long, in some cases):

• Short staple cotton is between 3/8” to 15/16” (.95cm to 2.4cm) in length
• Medium staple cotton is between 1” to 1-1/8” (2.54cm to 2.86cm) in length
• Long-staple cotton is between 1-3/16” to 2-1/2” (3cm to 6.35cm) in length

Properties of Cotton Products

• Comfortable – there are no surface characteristics of cotton that make it irritating to human skin. Cotton feels good against the skin; it has a soft hand.
• Hydrophilic – cotton has a natural affinity for water – it attracts moisture away from your body.
• Moisture passes freely through cotton – aiding in evaporation and cooling
• Good Heat Conductivity – Cotton allows heat to dissipate making it a wonderful fiber to maintain a comfortable sleeping temperature.
• Strong and abrasion resistance
• The unfavorable attributes of cotton include its lack of resiliency (cotton tends to wrinkle) and its
  lack of luster (colors are usually dull).

Properties of Cotton Fiber

• It has 8% moisture regain
• The cellulose is arranged in a way that gives cotton unique properties of strength, durability, and absorbency
• It is fresh, crisp, comfortable, absorbent, flexible, has no pilling problems, and has good resistance to alkalis
• It has poor wrinkle resistance, shrinkage, poor acid resistance, less abrasion resistance, is susceptible to damage by moths and mildew, needs lots of maintenance, and stains are difficult to remove
• Its fiber length ranges from ½ inches to 2inches
• It has a 10%increase in strength when wet.
• It has a flat twisted tube shape

Long Staple Cotton

In general, long-staple cotton is needed to spin the yarns needed in the weaving of the finer down proof cotton fabrics.

Long-staple cotton is considered to be finer quality because it can be spun into finer yarns and those finer yarns can be woven into softer, smoother, stronger, and more lustrous fabrics. Long-staple cotton makes stronger yarns, especially in fine yarns, as there are fewer fibers in a given length of yarn and the longer fibers provide more points of contact between the fibers when they are twisted together in the spinning process.

Common areas that grow long-staple cotton in the world would be Egypt, Sudan, the United States (Pima cotton grown in the west and southwest are long-staple cotton), and Western China. The two most widely known long-staple cotton are Egyptian cotton and Pima cotton. Pima cotton is grown mainly in the United States, but also in Peru, Israel, and Australia.

The fibers are sent to a textile mill where carding machines turn the fibers into cotton yarn. The yarns are woven into cloth that is comfortable and easy to wash but does wrinkle easily. Cotton fabric will shrink about 3% when washed unless pre-treated to resist shrinking.

Cotton is prized for its comfort, easy-care, and affordability and is ideal for clothing, bedding, towels, and furnishings.