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The Cotton Plant
The cotton plant belongs to the genus Gossypium of the family Malvaceae (mallow family). It is generally a shrubby plant having broad three-lobed leaves and seeds in capsules, or bolls; each seed is surrounded with downy fiber, white or creamy in color and easily spun. The fibers flatten and twist naturally as they dry.
Cotton is of tropical origin but is most successfully cultivated in temperate climates with well-distributed rainfall. All western U.S. cotton and as much as one-third of Southern cotton, however, is grown under irrigation. In the United States nearly all commercial production comes from varieties of upland cotton (G. hirsutum), but small quantities are obtained from sea-island and American-Egyptian cotton (both belonging to the species G. barbadense). G. arboreum and G. herbaceum are the chief cultivated species in Asia.
Cotton is classified in the division Magnoliophyta, class Magnoliopsida, order Malvales, family Malvaceae.
Planting and Production
Cotton is planted annually by seed in furrows; the plants are thinned and weeded during the spring growing season. Diseases and insect pests are numerous; of these the most destructive has been the boll weevil, which has caused enormous losses. Genetically altered strains of cotton are being developed that can resist infestation by some insects and damage by application of herbicides.
Mechanical harvesting is preceded by a chemical-defoliant spray to remove the leaves, leaving only the cotton bolls. In the ginhouse the cotton is separated from the seeds by a cotton gin and then baled. The usual plantation bale, weighing 500 lb (227 kg), is covered with jute and bound with iron hoops. The U.S. Dept of Agriculture has established standards for grades of cotton. The manufacture of cotton cloth involves many processes—carding, combing, and spinning—which transform raw fiber into yarn or thread strong enough for weaving.
Uses of Cotton
Innumerable commodities are made from cotton. From the lint (the fiber separated from the seed) come the major products, chiefly textile and yarn goods, cordage, automobile-tire cord, and plastic reinforcing. The linters (short, cut ends removed from the seed after ginning) are a valuable source of cellulose. Cotton hulls are used for fertilizer, fuel, and packing; fiber from the stalk is used for pressed paper and cardboard.
Production of the chief byproduct, cottonseed oil, has grown into a separate industry since its establishment in the late 19th cent. The oil content of cotton seeds is about 20%. After being freed from the linters, the seeds are shelled and then crushed and pressed or treated with solvents to obtain the crude oil. In its highly refined state, cottonseed oil is employed as salad and cooking oil, for cosmetics, and especially in the manufacture of margarine and shortenings. Paint makers use it to some extent as a semidrying oil. Less refined grades are used in the manufacture of soap, candles, detergents, artificial leather, oilcloth, and many other commodities. Cottonseed oil is increasingly important to cotton growers as cotton fiber meets competition from cheaper and stronger synthetic fibers.
Effect of the Cotton Gin
Cotton Production Today
See J. M. Munro, Cotton (2d ed. 1987); C. W. Smith and J. T. Cothren, ed., Cotton (1999); G. Riello, Cotton (2013); S. Beckert, Empire of Cotton (2014).
the fibers that cover the seeds of the cotton plant (Gossypium). When the plant matures, the fiber is harvested without removing the seeds; the harvested product is called seed cotton. During initial processing at gins, the seeds are separated to produce successively fibers mostly longer than 20 mm, fibers less than 20 mm long, and short fibers less than 5 mm long. The first category accounts for about one-third of the total mass of the seed cotton. Cotton is the most inexpensive and common type of textile fiber. It accounts for approximately 50 percent of the world production of textile fibers.
In Russian technical literature until the second half of the 19th century, the term khlopchataia bumaga (literally “cotton paper”) was used for cotton fiber instead of the current term khlopok. The adjectival derivative khlopchatobumazhnyi is still used, for example, in reference to the cotton industry and cotton fabric. In modern technical literature, the terms khlopok-volokno (“lint cotton”) and khlopok-syrets (“seed cotton”) are usually used instead of khlopok.
Cotton pressed into prism-shaped bales is delivered to spinning mills. In addition to fiber suitable for processing, the bale cotton contains various defective cotton fibers and contaminants, which reduce the quality of the cotton because they make the spinning process more difficult, decrease the output of yarn, and spoil the yarn’s appearance. The amount of waste material in cotton fiber depends primarily on the methods used for harvesting the seed cotton and for primary processing, but also on the cotton plant variety and the conditions of growth.
Cotton defects differ in degree of harmfulness and may be classified in three groups. First are fiber defects—tangles (packed and intertwined bundles of fibers) and flattened clusters of immature fibers. Such defects are broken into fiber by opening and carding machines during spinning. Most of the defective pieces are converted to yarn, and the rest become waste material. The second group of defects includes immature and crushed seeds and contaminants (parts of leaves, bolls, and branches of the cotton plant). During the spinning process they are separated into waste, which reduces the yarn output and makes the yarn more expensive. The third group includes the particularly undesirable defects—parts of seed husks with fibers and linters as well as very small clusters of tangled fibers. They are difficult to separate from the cotton, but they increase the thread breakage on the spinning machines and spoil the appearance of the articles produced.
Cotton is subdivided into two types, depending on the type of plant from which it is obtained and the most important qualitative characteristic, the fineness, or smallness of the cross section, of the fiber. The two classes are medium-fine and fine cotton; the latter has a longer and finer fiber. In the USSR fine cotton accounted for approximately 10 percent of the total production volume in 1976. It is produced from Soviet strains of fine-fiber cotton plants. All Soviet cottons are divided into seven grades, depending on breaking strength and degree of maturity: select (0), 1st, 2nd, 3rd, 4th, 5th, and 6th grades. In turn the cottons of grades 0 through 4 are subdivided into eight-types, depending on relative breaking strength and length. Cotton fiber of grades 5 and 6 is not subdivided into types.
Most cotton is processed for yarn; only a small portion of the cotton and linters is used to make medical garments, everyday apparel, furniture padding, and such products as packing and filters. Fibers shorter than 20 mm are also used in the chemical industry as a raw material from which synthetic fibers and yarns, films, lacquers, plastics, explosives, and other products are made.
Various textile products are made from cotton yarn, including fabrics, knitwear, nonwoven materials, sewing threads, twine, rope, and netting. Some textile goods are also produced from a blend of cotton with chemical and natural fibers.
REFERENCESOsnovnye napravleniia razvitiia narodnogo khoziaistva SSSR na 1976–1980goda. Moscow, 1975.
Kukin, G. N., and A. N. Solov’ev. Tekstil’noe materialovedenie, parts 1–2. Moscow, 1961–64.
Khafizov, I. K., and G. A. Tikhomirov. “Mirovoe proizvodstvo i potreblenie khlopka.” Tekstil’naia promyshlennost’. 1974, no 9.
A. N. SOLOV’EV