Cotton
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Cotton is a soft fiber that grows around the seeds of the cotton plant, a shrub native to the tropical and subtropical regions of both the Old World and the New World. The fiber is most often spun into thread and used to make a soft, breathable textile.
Cotton is a valuable crop because only about 10% of the raw weight is lost in processing. Once traces of wax, protein, etc. are removed, the remainder is a natural polymer of pure cellulose. This cellulose is arranged in a way that gives cotton unique properties of strength, durability, and absorbency. Each fiber is made up of twenty to thirty layers of cellulose coiled in a neat series of natural springs. When the cotton boll (seed case) is opened the fibers dry into flat, twisted, ribbon-like shapes and become kinked together and interlocked. This interlocked form is ideal for spinning into a fine yarn.
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History
Cotton has been used to make very fine lightweight cloth in areas with tropical climates for millennia. Some authorities claim that it was likely that the Egyptians had cotton as early as 12,000 BC, and evidence has been found of cotton in Mexican caves (cotton cloth and fragments of fiber interwoven with feathers and fur) which dated back to approximately 7,000 years ago. There is clear archaeological evidence that people in South America and India domesticated different species of cotton independently thousands of years ago.
The earliest written reference to cotton is in India. Cotton has been grown in India for more than three thousand years, and it is referred to in the Rig-Veda, written in 1500 BC. A thousand years later the great Greek historian Herodotus wrote about Indian cotton: "There are trees which grow wild there, the fruit of which is a wool exceeding in beauty and goodness that of sheep. The Indians make their clothes of this tree wool".
During the late medieval period, cotton became known as an imported fiber in northern Europe, without any knowledge of what it came from other than that it was a plant; people in the region, familiar only with animal fibers (wool from sheep), could only imagine that cotton must be produced by plant-borne sheep. John Mandeville, writing in 1350, stated as fact the now-preposterous belief: "There grew there India a wonderful tree which bore tiny lambs on the ends of its branches. These branches were so pliable that they bent down to allow the lambs to feed when they are hungry.". This aspect is retained in the name for cotton in many European languages, such as German Baumwolle, which translates as "tree wool".
By the end of the 16th century BC, cotton was cultivated throughout the warmer regions in Africa, Eurasia and the Americas.
The Indian cotton processing industry was eclipsed during the British Industrial Revolution, when the invention of the Spinning Jenny (1764) and Arkwright's spinning frame (1769) enabled cheap mass-production of cotton cloth in the UK. Production capacity was further improved by the invention of the cotton gin by Eli Whitney in 1793.
In the United States, growing the three crops, cotton, indigo and tobacco historically were the leading occupations of slaves. After emancipation, the share cropping system evolved which in many cases differed little from the systems of slavery.
Production
Today cotton is produced in many parts of the world, including Europe, Asia, Africa, the Americas and Australia, using cotton plants that have been selectively bred so that each plant grows more fiber. In 2002, cotton was grown on 330,000 km² of farmland. 47 billion pounds (21 million t) of raw cotton worth 20 billion dollars the US was grown that year.
The cotton industry relies heavily on chemicals such as fertilizers and insecticides, although some farmers are moving towards an organic model of production, and chemical-free organic cotton products are now available. Historically, one of the most economically destructive pests in cotton production has been the boll weevil.
Most cotton is harvested mechanically, either by a cotton picker, a machine that removes the cotton from the boll without damaging the cotton plant or by a cotton stripper which strips the entire boll off the plant. Cotton strippers are generally used in regions where it is too windy to grow picker varieties of cotton and generally used after the application of a defoliant or natural defoliation occurring after a freeze. Cotton is a perennial crop in the tropics and without defoliation or freezing, the plant will continue to grow. Cotton is a close relative of okra and hibiscus.
The logistics of cotton harvesting and processing have been improved by the development of the cotton module builder, a machine that compresses harvested cotton into a large block, which is then covered with a tarp and temporarily stored at the edge of the field.
Cotton processing
After cultivation, cotton is harvested at the farm, and goes through multiple processes. Before processing, there are 3 stages:
After weaving, cotton typically fabric passes through several processing stages. After some stages the fabric can be directly used in the final product, for example unbleached cloth is used in grain bags. Typical stages are:
Uses
In addition to the textile industry, cotton is used in fishnets, coffee filters, tents and in bookbinding. The first Chinese paper was made of cotton fiber, as is the modern US dollar bill and federal stationery. Fire hoses were once made of cotton.
Denim, a type of durable cloth, is made mostly of cotton, as are T-shirts.
The cottonseed which remains after the cotton is ginned is used to produce cottonseed oil, which after refining can be consumed by humans like any other vegetable oil. The cottonseed meal that is left is generally fed to livestock.
Fair trade
Cotton is an enormously important commodity throughout the world. However, many farmers in developing countries receive a low price for their produce, or find it difficult to compete with developed countries. This has led to 'fair trade' cotton clothing being available in some countries.
Old British cotton yarn measures
- 1 thread = 54 inches (c. 137 cm)
- 1 skein or rap = 80 threads (120 yards or c. 109 m)
- 1 hank = 7 skeins (840 yards or c. 768 m)
- 1 spindle = 18 hanks (15,120 yards or c. 13.826 km)
References and further reading
- The Thames and Hudson Manual of Dyes and Fabrics, Joyce Storey, 1978
- Photo documentation and commentary on collateral damage to the environment from cotton spraying (http://gardenbees.com/cotton%20spray/cottonspray.htm)
External links
- Cotton Incorporated (http://www.cottoninc.com/) - a cotton industry trade groupbg:Памук
cs:Bavlna da:Bomuld de:Baumwolle es:Algodón eo:Kotono fr:Coton it:Cotone (fibra) he:כותנה nl:Katoen ja:綿 pl:Bawełna (włókno) pt:Algodão fi:Puuvilla sl:bombaž simple:Cotton sv:Bomull