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Home , Cotton, Fiber, Singe

: From Field to Fabric

Cotton Cotton remains the most stock, dairy and poultry feed. More miraculous under the than 154 million gallons of cotton- sun, even after 8,000 years. oil are used No other fiber comes close for food prod- to duplicating all of the desir- ucts ranging able characteristics combined from margarine in cotton. and cooking oils The fiber of a thousand faces and to salad dressing. almost as many uses, cotton is noted for its The average U.S. crop moving versatility, appearance, and above all, its from the field through cotton natural comfort. From all types of apparel, including gins, warehouses, oilseed mills astronauts’ in-flight space , to sheets and , and mills to the consumer, and tarpaulins and , cotton in today’s fast-moving accounts for more than $35 billion world is still nature’s wonder fiber. It provides thou- in products and services. This injec- sands of useful products and supports millions of jobs tion of spending is a vital element in the health of rural as it moves from field to fabric. economies in the 17 major cotton-producing states from Virginia to . Economics of Cotton The gross dollar value of cotton and its extensive A National Cotton Council analysis affirms that today’s system of production, harvesting and ginning provides modern cotton production system provides significant countless jobs for mechanics, distributors of farm benefits to rural America’s economy and environment. machinery, consultants, crop processors and people Healthy rural economies are based on stable farm in other support services. Other allied industries income, and cotton yields and are often among such as banking, transportation, warehousing and the healthiest of all field crops, or . merchandising also benefit from a viable U.S. cotton Cotton continues to be the basic resource for thou- production system. sands of useful products manufactured in the U.S. and Annual business revenue stimulated by cotton in the overseas. U.S. textile manufacturers use an annual U.S. economy exceeds $120 billion, making cotton average of 7.6 million bales of cotton. A America’s number one value-added crop. bale is about 500 pounds of The farm value of U.S. cotton and produc- cotton. More than half of this tion is approximately $5 billion. quantity (57%) goes into Overseas sales of U.S. cotton make a significant con- apparel, 36% into home fur- tribution to the reduction in the U.S. trade deficit. nishings and 7% into industrial Annual values of U.S. cotton sold overseas have aver- products. If all the cotton pro- aged more than $2 billion. Recently, the U.S. has sup- duced annually in the U.S. plied over 10.5 million bales of the world’s cotton were used in making a single , accounting for about 37% of the total world product, such as blue or men’s market. The largest customers for U.S. cotton , it would make more than 3 billion pairs of jeans are Asia and . and more than 13 billion men’s dress shirts. Exports of , and other U.S.-manufactured An often-overlooked component of the crop is the vast cotton products have increased dramatically since the amount of cottonseed that is produced along with the early 1990s, from 1.38 million bale equivalents in fiber. Annual cottonseed production is about 6.5 billion 1990, to more than 4 million bale equivalents in 1998. tons, of which about two-thirds is fed whole to live- stock. The remaining seed is crushed, producing a high-grade salad oil and a high meal for live- Crop Production Weed Control The Cotton spans the southern half of the Unites Cotton grows slowly in the spring and can be shaded States, from Virginia to California. Cotton is grown in out easily by weeds. If weeds begin to overpower the 17 states and is a major crop in 14. Its growing season seedling cotton, drastic reductions in yield can result. of approximately 150 to 180 days is the longest of any Later in the season, cotton leaves fully shade the annually planted crop in the country. Since there is ground and suppress mid-to-late season weeds. For much variation in climate and , production practices these reasons, weed control is focused on providing a 6 differ from region to region. In the western states, for to 8-week weed-free period directly following planting. example, nearly the entire crop is irrigated. Producers employ close cultivation and planters that Planting begins in February in south and as late place the cottonseed deep into moist soil, leaving as June in northern areas of the . Land weed in high and dry soil. or cultiva- preparation actu- tion controls weeds between the rows. ally starts in the fall, shortly after Insect Management harvest. Stalks The cotton has evolved with numerous damag- from the old crop ing insects. These insects, if left unattended, would are shredded to virtually eliminate the harvestable crop in most cotton- reduce food sup- producing areas. infested with leaf-feeding plies for over- insects are able to compensate somewhat by produc- wintering pests. ing more leaves. Many of cotton’s insects, however, Usually, this feed on squares and bolls. This reduces the yield and residue is left on the surface to protect the soil from leads to delays in crop development, often into the erosion. The use of heavy mechanical harvesters com- or rainy season. pacts the soil, sometimes requiring tillage to loosen The cotton industry utilizes a multifaceted approach to the soil for the next crop’s . the problem of insects. Known as Integrated Pest Planting Management (IPM), it keeps pests below yield-damag- ing levels. IPM is dependent on natural populations of Planting is accomplished with 6, 8, 10 or 12-row preci- beneficial insects to suppress damaging pests. sion planters that place the seed at a uniform depth Additionally, some cotton varieties are genetically bred and interval. Young cotton seedlings emerge from the to be less attractive to insects. soil within a week or two after planting, depending on temperature and moisture conditions. Squares, or Some plants are improved by modern biotechnology, flower buds, form a month to six weeks later which causes the plant to be resistant to certain and creamy to dark yellow blossoms damaging worms. Other modern biocontrol appear in another three weeks. strategies also are used. For example, Pollen from the flower’s stamen is where populations of damaging pink carried to the stigma, thus polli- bollworm insects break out, sterile nating the ovary. Over the next insect releases are used to target the three days, the blossoms gradual- pest and minimize disruption to the ly turn pink and then dark red beneficial insects. Also, cultural prac- before falling off, leaving the tiny fer- tices that promote earliness and short- tile ovary attached to the plant. It ripens season production reduce the vulnerability and enlarges into a pod called a cotton boll. of cotton production to pests. Plant protection chemicals are often used to prevent devastating crop Individual cells on the surface of seeds start to elon- losses to insects. All plant protection methods used on gate the day the red flower falls off (abscission), plants in the U.S. are thoroughly evaluated by the reaching a final length of over one inch during the first Environmental Protection Agency (EPA) to assure month after abscission. The thicken for the next food safety and protection to humans, animals and to month, forming a hollow cotton fiber inside the watery the environment. boll. Bolls open 50 to 70 days after bloom, letting air in to dry the white, clean fiber and fluff it for harvest. Plant Diseases Harvesting Cotton diseases have been contained largely through While harvesting is one of the final steps in the produc- the use of resistant cotton varieties. Rotation to non- tion of cotton crops, it is one of the most important. host crops such as grain or corn also breaks the dis- The crop must be harvest- ease cycle. Nematodes, while not truly a disease, ed before weather can cause the plant to exhibit disease-like symptoms. damage or completely ruin Nematodes are microscopic worm-like organisms that its quality and reduce yield. attack cotton’s roots causing the plant to stop growing, Cotton is harvest- and as a result, causes reduced yield. Crop rotation is ed in the U.S., beginning in the primary method of managing for nematodes. July in south Texas and in Soil Conservation October in more northern areas of the Belt. Cotton producers expend extra efforts to minimize soil Stripper harvesters, used erosion. Cotton is sensitive to wind-blown soil because chiefly in Texas and the plant’s growing point is perched on a delicate Oklahoma, have rollers or stem, both of which are easily damaged by abrasion mechanical brushes that remove the entire boll from the from wind-blown soil. For that reason, many farmers plant. In the rest of the Belt, pickers are used. use minimum tillage practices which leave plant These cotton pickers pull the cotton from the open bolls residue on the soil surface thereby preventing wind using revolving barbed spindles that entwine the fiber and erosion. and release it after it has separated from the boll. Conservation tillage, the practice of covering the soil in crop residue year ‘round, is common in windy areas. A Seed Cotton Storage growing number of producers also are moving to mini- Once harvested, seed cotton must be removed from the mum tillage, or a no-till system, to reduce soil move- harvester and stored before it is delivered to the gin. ment. In the rain belt, land terracing and contour tillage Seed cotton is removed from the harvester and placed are standard practices on sloping land to prevent the in modules, relatively compact units of seed cotton. A washing away of valuable topsoil. cotton module, shaped like a giant bread loaf, can weigh up to 25,000 pounds. The cotton plant’s system is very efficient at seek- Ginning ing moisture and from the soil. From an eco- From the field, seed cotton moves to nearby gins for nomic standpoint, cotton’s water use efficiency allows separation of and seed. The cotton first goes cotton to generate more revenue per gallon of water through dryers to reduce moisture content and then than any other major field crop. through cleaning equipment to remove foreign matter. Most of the U.S. cotton acreage is grown only on rain These operations facili- moisture. A trend toward supplemental irrigation to tate processing and carry a field through drought has increased in acreage improve fiber quality. and helped stabilize yields. Cotton’s peak need for The cotton is then air water occurs during July, when it is most vulnerable to conveyed to gin stands water . A limited supply of irrigation water is where revolving circular being stretched saws pull the lint over many acres through closely spaced via the use of high- ribs that prevent the ly efficient irriga- seed from passing through. The lint is removed from tion methods such the saw teeth by air blasts or rotating brushes, and as low energy pre- then compressed into bales weighing approximately cision applications, 500 pounds. Cotton is then moved to a warehouse for sprinklers, surge storage until it is shipped to a textile mill for use. and drip irrigation. A typical gin will process about 12 bales per hour, Not only has irrigation stabilized yields for many grow- while some of today’s more modern gins may process ers, it also has allowed production in the desert states as many as 60 bales an hour. of California, Arizona and New Mexico. Classing Cottonseed After the lint is baled at the Cotton actually is two crops, fiber and seed. About gin, samples taken from one-third of the cottonseed produced from a typical each bale are classed crop is crushed for oil and meal used in food products according to fiber strength, and in livestock and poultry feed. length, length uniformity, For each 100 pounds of fiber produced by the cotton color, non-fiber content and plant, it also produces about 162 pounds of cotton- fineness using high volume seed. Approximately 5 percent of the total seed crop is instrumentation (HVI) and the aid of an expert called a reserved for planting; the remainder is used for feed- Classer. Scientific quality control checks are made ing as whole seeds or as raw material for the cotton- periodically to ensure that instrument and Classer seed processing industry. accuracy is maintained. After being separated from the lint at the gin, the Cotton of a given variety produces fibers of approxi- cotton’s seed is transported to a cottonseed crushing mately the same length. Since the fibers may vary mill. There it is cleaned and conveyed to delinting within a bale, length uniformity allows a determination which, operating on the same principle as a of the variability within that bale. gin, remove the remaining short fibers which are Other quality factors also are important. The fiber’s known as linters. The linters go through additional fineness is important for determining the type of processing steps before being made into a wide that can be made from the fiber—the finer the cotton variety of products ranging from mattress stuffing to fibers, the finer the yarns. Color or brightness of the photographic film. fibers also is important. Cotton that is very white gen- After the linters are removed, the seed is put through a erally is of higher value than whose color may machine that employs a series of knives to loosen the have yellowed with exposure to elements before har- hulls from the kernel. The seeds are then passed vesting. Cotton, being a biological product, typically through shakers and beaters. The separated hulls are contains particles of cotton leaves called trash. The marketed for livestock feed or industrial products, and amount of trash also influences the cotton’s value the kernels are since the textile mill must remove trash before pro- ready for the cessing. The fiber’s strength also is an important extraction of oil, measurement that ultimately influences the fabrics the seed’s most made from these fibers. The U.S. Department of valuable by- Agriculture (USDA) establishes classing standards in product. Solvent cooperation with the entire cotton industry. extraction or Marketing presses remove the oil. After fur- Cotton is ready for sale after instrument classing ther processing, establishes the quality parameters for each bale. The the oil is used in marketing of cotton is a complex operation that cooking or salad oil, shortening and margarine. Limited includes all transactions involving buying, selling or quantities also go into soaps, pharmaceuticals, cosmet- reselling from the time the cotton is ginned until it ics, textile finishes and other products. reaches the textile mill. The remaining meat of the kernel is converted into Growers usually sell meal, the second most valuable by-product. High in their cotton to a protein, it is used in feed for all classes of livestock local buyer or mer- and poultry. chant after it has Cottonseed meal makes an excellent natural been ginned and for lawns, flower beds and gardens. baled, but if they decide against Yarn Production immediate sale they Modernization efforts have brought major changes to can store it and bor- the U.S. . Equipment has been stream- row money against lined and many operations have been fully automated it. Since it is a non-perishable crop, cotton stored in a with computers. Machine speeds have greatly government-approved warehouse provides a secure increased. basis for a monetary loan. At most mills the opening of cotton bales is fully Fabric automated. Cotton fabric manufacturing starts with the preparation Lint from several bales is mixed and blended together of the yarn for or . Annually, textile to provide a uniform blend of fiber properties. To mills in the U.S. normally produce about eight billion ensure that the new high-speed automated feeding square yards each of woven and three billion square equipment performs at peak efficiency and that fiber yards of knitted cotton goods. properties are consistent, computers group the bales for production/feeding according to fiber properties. Woven Fabrics The blended lint is blown by air from the feeder through Weaving is the oldest method of making yarn into fab- chutes to cleaning and machines that separate ric. While modern methods are more complex and and align the fibers into a thin web. Carding machines much faster, the basic principle of interlacing yarns can process cotton in excess of 100 pounds per hour. remains unchanged. The web of fibers at the front of the card is then On the loom, drawn through a funnel-shaped device called a trumpet, lengthwise yarns providing a soft, -like strand called a sliver called the warp form (pronounced SLY-ver). the skeleton of the As many as eight strands of sliver are blended togeth- fabric. They usually er in the process. Drawing speeds have require a higher increased tremendously over the past few years and degree of twist than now can exceed 1,500 feet per minute. the filling yarns Roving frames draw or draft the slivers out even more that are interlaced thinly and add a gentle twist as the first step in ring widthwise. of yarn. Traditionally, cloth was woven by a wooden shuttle that Ring spinning moved horizontally back and forth across the loom, machines further interlacing the filling yarn with the horizontally, length- draw the roving and wise warp yarn. Modern mills use high-speed shuttle- add twist making it less weaving machines that perform at incredible rates tighter and thinner and produce an endless variety of fabrics. Some carry until it reaches the the filling yarns across the loom at rates in excess of yarn thickness or 2,000 meters per minute. “count” needed for The rapier-type weaving machines have metal arms or weaving or knitting rapiers that pick up the filling and carry it fabric. The yarns can be twisted many times per inch. halfway across the loom where another rapier picks it Ring spinning frames continue to play a role in this up and pulls it country, but open-end spinning, with rotors that can the rest of the spin five to six times as fast as a ring spinning machine, way. Other types are becoming more widespread. In open-end spinning, employ small yarn is produced directly from sliver. The roving process projectiles that is eliminated. pick up the filling thread and carry Other spinning systems have also eliminated the need it all the way for roving, as well as addressing the key limitation of across the loom. both ring and open-end spinning, which is mechanical Still other types twisting. These systems, air jet and Vortex, use com- employ compressed air to insert the filling yarn across pressed air currents to stabilize the yarn. By removing the warp. In addition to speed and versatility, another the mechanical twisting methods, air jet and Vortex are advantage of these modern weaving machines is their faster and more productive than any other short- relatively quiet operation. spinning system. There are three basic weaves with numerous varia- After spinning, the yarns are tightly wound around tions, and cotton can be used in all of them. The plain bobbins or tubes and are ready for fabric forming. Ply weave, in which the filling is alternately passed over yarns are two or more single yarns twisted together. one warp yarn and under the next, is used for , Cord is plied yarn twisted together. percales, chambray, and many other fabrics. The weave, in which the yarns are interlaced to The flat is another basic type. form diagonal ridges across the fabric, is used for sturdy Designed with a flat bed, it has dozens of needles fabrics like denim, , and . arranged in a straight line and produces a knit fabric The weave, the least common of the three, pro- that is flat, similar to . duces a smooth fabric with high sheen. Used for cot- A flat knitting machine makes over one million stitches ton , it is produced with fewer yarn interlacings a minute, and can be set to drop or add stitches auto- and with either the warp or filling yarns dominating the matically in order to narrow or widen the fabric at cer- “face” of the cloth. tain points to conform to specific shapes. In some plants, optical scanners continuously monitor Knitting machines can be programmed to produce a fabric production looking for flaws as the cloth wide variety of fabrics and shapes. emerges from the weave machine. When imperfec- tions appear, computers immediately print out the Fabrics location of the flaw so that it can be removed later dur- Cotton fabrics, as ing fabric inspection. they come from the loom in their rough, Knitted Fabrics unfinished stages, Knitting is a method of constructing fabric by using a are known as greige series of needles to interlock loops of yarn. goods. Most under- Lengthwise rows of these loops, comparable to the go various warp yarn in woven goods, are called wales. processes to meet Crosswise rows, comparable to filling yarns, are specific end-use requirements. known as courses. Some mills, in addition to spinning and weaving, also There are numerous similarities in knitting done by or print their fabrics and finish them. Others sell hand and machine, but there are also some marked greige goods to converters who have the cloth fin- differences. ished in independent plants. Most cotton is knit on circular machines which have Finishing processes are numerous and complex, needles fixed to the rim of a rotating cylinder. As the reflecting today’s tremendous range and combination of cylinder turns, colors, textures and special qualities. the needles In its simplest form, finishing includes cleaning and work their way preparing the cloth, or printing it and then treat- from to ing it to enhance performance characteristics. stitch producing To produce a smooth surface in preparation for dyeing a tubular fabric. and finishing, the greige goods are passed rapidly Its width is regu- over gas-fired jets or heated copper plates to off lated by the size lint and loose threads. of the cylinder, Moving at speeds that can be greater than 200 yards which usually a minute, the material is scoured and bleached in a ranges from 9 to 60 inches in diameter. continuous process that involves the use of hydrogen A hand knitter uses two needles forming one stitch at peroxide. The time for the chemicals to do the prepa- a time. ration reactions occurs from piling the fabric on con- Depending on the width of fabric desired, a modern veyor belts that pass through steaming chambers, or knitting machine might use over 2,500 needles. stacking in large steam-heated, J-shaped boxes Instead of a single cone of yarn, a knitting machine before the goods are withdrawn from the bottom. may have up to four cones per inch of fabric width. For If a more lustrous cloth is desired, the goods are example, a machine with a 32-inch cylinder can have immersed under tension in a caustic soda solution and over 2,700 needles and 128 cones of yarn feeding then later neutralized. The process, called merceriz- simultaneously. These are typical statistics for a ing, causes the fiber to swell permanently. This gives machine used in making underwear knits, but figures the fabric a silken sheen, improves its strength and vary according to the type of machine used and the increases its affinity for dye. Mercerizing also can be fabrics produced. done at the yarn stage. Dyeing Printing The most commonly used processes for imparting Printing colored designs on cotton cloth is similar to color to cotton are piece dyeing and yarn dyeing. printing on . In piece dyeing, which is used primarily for fabrics that Long runs of the same fabric design are produced on are to be a color, a continuous length of dry cloth a roller print machine operating at speeds between 50 is passed full-width through a trough of hot dye solu- to 100 yards a minute. As many as of 10 different col- tion. The cloth then goes between padded rollers that ors can be printed in one continuous operation. squeeze in the color evenly and removes the excess A typical printing machine has a large padded drum or liquid. In one cylinder, which is surrounded by a series of copper variation of this rollers, each with its own dye trough and doctor blade basic method, that scrapes away excess dye. The number of rollers the fabric, in a varies according to the fabric design, since each color rope-like coil, is in the design is etched on a separate roller. As the processed on a cloth moves between the rotating drum and rollers reel that passes under great pressure, it picks up color from the in and out of a engraved area of each roller in sequence. The printed dye beck or vat. cloth is dried immediately and conveyed to an oven Yarn dyeing, that sets the dye. which occurs Automatic screen-printing is another principal method before the cloth is woven or knitted, is used to for imparting colored designs to cotton fabrics. Although produce gingham checks, plaids, woven stripes and slower than roller printing, it has the advantage of pro- other special effects. Blue dyed warp yarns, for ducing much larger and more intricate designs, elabo- example, are combined with white filling yarns in rate shadings and various handcrafted effects. denim construction. In flat bed screen-printing, the fabric design is repro- One of the most commonly used yarn dyeing methods duced on fine screens, one for each color. On is package dyeing. In this system, yarn is wound on each screen, the areas in the design that are not to be perforated cylinders or packages and placed on verti- penetrated by the dye are covered with lacquer or cal spindles in a round dyeing machine. some other dye-resistant coating. The screens are coat- Dye solution is forced alternately from the outside of ed with dye on the back and mounted in the proper the packages inward and from the inside out under sequence above a flat bed. As a belt carries the fabric pressure. along from screen to screen, a squeegee or roller Computers are used increasingly in dyeing processes presses the dye through the open area of the screen to formulate and match colors with greater speed and onto the fabric. accuracy. The new flat bed machines can have speeds of up to 1,200 yards per hour for a fabric with a 36-inch design repeat. Faster by far are the recently developed rotary screen printing machines with production speeds of up to 3,500 yards an hour. The system combines roller and screen printing, utilizing perforated cylinders instead of flat screens. The color paste is fed inside the cylinders and a small metal roller forces the color through the pores of the cylinder onto the fabric which is moving continuous- ly under the cylinders. As many as 16 colors can be printed on one fabric using this method. Use of this technique is increasing since the screens or cylinders can be produced less expensively than the engraved copper rollers used in roller printing. Finishing Cotton is used for virtually every type of , from coats and jackets to foundation garments. Most of its Finishing, as the term implies, is the final step in fabric apparel usage, however, is for men and boys’ clothing. production. Cotton supplies over 70% of this market, with jeans, Hundreds of finishes can be applied to textiles, and the shirts and underwear being major items. methods of application are as varied as the finishes. In home Cotton fabrics are probably finished in more different furnishings, ways than any other type of fabrics. cotton’s Some finishes change the look and feel of the cotton uses range fabric, while others add special characteristics such as from bed- durable press, water repellency, flame resistance, spreads to shrinkage control and others. window Several different finishes may be applied to a single shades. It fabric. is by far the dominant Cotton’s Major Uses fiber in tow- U.S. textile mills presently consume approximately els and 7.6 million bales of cotton a year. Eventually, about washcloths, supplying almost 100% of that market. 57% of it is converted into apparel, more than a Cotton is popular in sheets and pillowcases, where it third into home furnishings and the remainder into holds over 60% of the market. industrial products. Industrial products containing cotton are as diverse as Cotton’s competitive share of U.S. produced textile wall coverings, and tapes. The end-uses shows a steady increase, presently standing biggest cotton users in this category, however, are at approximately 34%. Cotton’s share of the retail medical supplies, industrial thread and tarpaulins. apparel and home furnishings market has grown from a historic low of 34% in the early 1970s to more than 60% today.

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