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Production of cotton canvas
 

Cotton canvas is one of the world's major textiles. It is also one of the most versatile, being used either alone or in many blends for a seemingly infinite variety of apparel and household and industrial products.

Cotton is the fibrous matter that surrounds the seeds of various shrubs or woody herbs of the mallow family,Malvaceae. The cotton fiber is obtained from multi-stemmed bushy plants that grow from 3 to 5 feet in height. Cotton fiber is composed of 87% - 90% cellulose, similar to the cellulose found in other natural products such as wood and linen. Cotton does contain very small amounts of other substances, however, such as minerals, waxes and pectic products. They serve to protect the cotton plant from the weather.

There are four main types of cotton from which cotton canvas can be made from: American Upland, Egyptian, Sea Island and Asiatic. All four types of cotton resemble one another in appearance, but bear flowers of different colours that bloom at varying times and have different fiber characteristics. American upland is grown in almost every cotton-producing country and makes up 90% of the world crop.

American upland is a plant with cream-coloured flowers and stands 1 to 7 inches in height. It gives a large yield, with white fibers 7/8 to 11/4 inches in length. The Egyptian type of cotton has lemon-coloured flowers and produces long silky light tan fibers 11/2 inches in length. The American variant of this strain is prima cotton, which yields fibers 13/8 inches in length. Sea island cotton is grown in the West Indies. It has yellow flowers and is a slow grower. It produces a low yield of white flowers 13/4 inches long, used for high-quality textiles. The Asiatic strain produces a low yield of short, coarse, harsh cotton fibers. It is rapidly being replaced by other types.

Production

Cotton grows best in fertile, well-drained soil. It must have good moisture, but requires dry conditions after the cotton balls are fully mature. Cotton seed is sown in ploughed soil or soil that has slight ridges in it. Today the planting process is highly mechanized, and the cotton plants are fertilized and often treated with insecticide at the same time. When the cotton plants have begun to grow sufficiently they are thinned to avoid overcrowding and to assure that the cotton plants are in rows.

As the cotton plants mature they bear numerous pink-white flowers. When the flowers fade, seed pods (bolls) remain that contain up to eight cotton seeds. As the seeds begin to develop they are covered with a white fluff or fiber. Before the cotton plant is fully mature, or ripe, the cotton fiber is shaped much like a cylindrical tube throughout which a substance called lumen is found. The growing process continues until each seed becomes completely enclosed with as many as 4000 cotton fibers. As the cotton fiber grow and expand, the boll bursts. When the cotton fiber is thus exposed to the sun, the lumen dries up, causing the cotton fiber to flatten and twist. During this period in its development it is essential that there not be heavy rainfall.

The cotton is collected by large harvesting machines. Before the advent of this important piece of equipment all of the cotton was painstakingly picked by hand. The harvesting machine collects the bolls but does not separate the seeds from the cotton fiber. Originally the cotton seeds had to be removed by hand, but the process was made more efficient by the invention of the cotton gin. During the ginning process the cotton is fed into the gin, where the cotton fibers are removed from the seeds. The process also separates the more desirable (½ to 2 inch) cotton fibers from the short cotton fibers.

The short cotton fibers, referred to as lint, are not used for yarn or thread but are an important raw material as a convenient and cheap source of cellulose, which is the basis of many rayons. The separated cotton seeds are then used for other by-products such as cottonseed oil. After ginning the cotton still contains a certain amount of dust and twigs and is referred to as raw cotton. It is at this point that the cotton is compressed into huge bales that are distributed to the mills that will manufacture it into yarn and fabric.

Cotton and cotton canvas is produced in many countries around the world, with the largest producers being China, the United States, the Soviet Union, India and Pakistan.

More on qualities and classification of cotton canvas

More on properties of cotton canvas

More on artist unprimed cotton canvas

Back to cotton canvas main page

 


 
 
   

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