Section+1.1A

=Cotton = Home, Section 1.1, Section 1.1B, Section 1.1C, Section 1.2, Section 1.3

Cotton is the most widely used seed hair fiber. Cotton was once the most used single fiber until it was passed in use and production by the synthetic fiber polyester. Even though the production of synthetics has seen significant growth, cotton has still continued its large share of the world market and its image as a comfortable natural fiber.

Cotton fibers grow in the boll, or seed pod; each fiber is a single plant cell that develops as an elongation of a cell in the outer layer, or epidermis, of the cotton seed. These seed hairs are called //lint//. A secondary growth of much shorter fibers accompanies the growth of cotton lint. These fibers, which are too short to be spun into yarn, are called //linters//.
 * The Cotton Plant**

Cotton fibers are sometimes classified according to the length to which they grow. Longer fibers command higher prices because they are usually also finer. Major classifications are listed as follows: 1. __Short-staple fiber__: 3/8 to 3/4 inches in length. Short fibers come from Asiatic species of cotton that are both short and coarse. 2. __Intermediate-staple fiber__: 13/16 to 1 and 1/4 inches in length. The variety known as American Upland is of intermediate length and coarseness. This variety of cotton makes up by far the largest quantity of cotton fiber grown in the United States. 3. __Long-staple fiber__: 1 and 1/2 to 2 and 1/2 inches. This includes varieties known as Sea Island, Egyptian, and pima (or America-Egyptian), all of which are used for good-quality cotton fabric. Peruvian and Brazilian fibers also fall into this classification. However, the Peruvian variety, known as //tanquis//, has a slight crimp and rougher feel, somewhat like that of wool, with which it is sometimes blended.
 * Types of Cotton**

Physical Properties (Image taken from http://chestofbooks.com/crafts/needlework/Clothing-And-Health/Lesson-2-The-Story-Of-Cotton-Growing.html) Mechanical Properties Chemical Properties Environmental Properties Other Properties
 * Properties of Cotton**
 * Color. Cotton fiber is generally white to tan in color. Naturally colored cottons do not require either dyeing or bleaching, processes that generate significant levels of waste water.
 * Shape. The length of an individual cotton fiber is usually from one thousand to three thousand times its diameter, which may range from sixteen to twenty microns. The fiber has a U-shaped or kidney bean-shaped cross-section with a central canal known as the //lumen//. During growth this channel carries nutrients to the developing fiber. After the fiber has reached its full length, layers of cellulose are deposited on the inside of the thin, waxy, exterior wall. The fiber grows much as a tree does, with concentric rings of growth. Each layer is made up of small fibrils and as these fibril layers are deposited, they form a complex series of spirals that reverse direction at some points. The spiraling of the cellulose fibrils causes the characteristic twists, or //convolutions//, in the lengthwise direction of the fiber (see image below).
 * Luster. The luster of cotton is low unless it has been given special treatments or finishes. This is, in part, a consequence of the natural twist of cotton and its resultant uneven surface that breaks up and scatters light rays reflected from the fiber surface.
 * Specific Gravity. Cotton has a specific gravity of 1.54. This means that cotton fabrics feel heavier in weight than comparable fabrics made from polyester or nylon.
 * Strength. Strength of cotton on a scale of high, medium, and low would rank as a medium. The strength is increased by the length of the polymer chains. In comparison with other cellulosic fibers, cotton is weaker than flax and stronger than rayon. Cotton is 10 to 20 percent stronger when wet than when dry.
 * Modulus. Cotton fibers have a moderately high modulus, similar to that of polyester. This helps the two fibers to blend well. It also means that cotton fibers are not very stretchable.
 * Elongation and Recovery. Like most other cellulosic fibers, cotton has low elongation and elastic recovery. Knitted cotton cuffs and bands may stretch during wear and care and may not recover fully.
 * Resilience. Cotton fabrics also wrinkle easily and do not recover well from wrinkling. In stretching or wrinkling, hydrogen bonds between chains are broken then reformed in the new position, holding the wrinkle or other deformation. Through the application of durable press finishes, however, resilience can be improved. Unfinished cotton fabrics generally must be ironed after laundering.
 * Flexibility. Compared to many other fibers, cotton is fairly flexible. However, when fineness is taken into account, its bending resistance on a relative scale is high, affecting the drapability of cotton fabrics.
 * Absorbency and Moisture Regain. Because of its many hydroxyl groups, which attract water, cotton is an absorbent fiber. Its good absorbency makes cotton comfortable in hot weather and suitable for materials where absorbency is important (such as towels). Cotton dries slowly because the absorbed moisture must be evaporated from the fiber. Due to their high absorbency, cotton fibers take waterborne dyes readily. The percentage moisture regain of cotton is 7 to 8 percent at standard testing conditions of temperature and humidity.
 * Heat and Electrical Conductivity. Cotton conducts electricity and, thus, does not build up static electrical charges. It has moderately high heat conductivity, which makes the fabric comfortable in hot weather.
 * Effect of Heat; Combustibility. Cotton is not thermoplastic and, therefore, does not melt. Exposure to dry heat at temperatures about 300 degrees Fahrenheit, however, causes gradual decomposition and deterioration of the fiber. Excessively high ironing temperatures cause cotton to scorch or turn yellow. Cotton is combustible. It burns upon exposure to a flame and continues to burn when the flame has been removed. Burning cotton fabric smells like burning paper, and a fluffy, gray ash residue remains. It is not possible to distinguish cotton from other cellulosic fibers by burning.
 * Chemical Reactivity. Strong acids degrade the fibers, producing holes in cotton fabrics. Organic solvents have no harmful effect, allowing cotton fabrics to be dry cleaned.
 * Resistance to Microorganisms and Insects. If cotton is stored in damp, warm, dark places, it is likely to have mildew growth on the fibers. This fungus growth can stain and eventually rot and degrade the fibers. Other bacteria and fungi that are commonly found in soiled, moist areas will also deteriorate or rot cotton fabrics.
 * Resistance to Environmental Conditions. Compared to other fibers, cotton shows a better resistance to sunlight; however, prolonged sunlight exposure will cause weakening and deterioration of cotton fabrics. When used for draperies or curtains, they will last longer if they are lined with another layer of fabric. Cotton fabrics are not generally affected by their age, but it is important to store the fabrics in clean conditions and in dry areas to prevent mildew. If needed, special acid-free tissue paper can be used to store antique cotton garments, cotton quilts, and spreads. Ordinary tissue paper should not be used for wrapping fabrics for long-term storage because the paper contains an acid residue that may damage or yellow the cloth.
 * Dimensional Stability. Cotton fibers swell considerably in the transverse direction when wet. Unfinished woven or knitted cotton fabrics will shrink in the first few washings because the washing releases tensions created during weaving or finishing. The relaxation of these tensions may cause changes in the fabric dimensions. Cotton fabrics can be given special finishes to prevent this relaxation shrinkage.
 * Abrasion Resistance. Fabrics made from cotton generally have low abrasion resistance. Garments will show wear at hems, cuffs, and collars; all-cotton sheets will not be as durable as those that are blends with more abrasion-resistant fibers such as polyester. Cotton fabrics will not, however, pill badly. (Pilling is the process when small beads of fabric form on the surface from being rubbed and worn after a period of time.)

Cotton fabrics are used for a wide variety of products. Its versatility and low cost make it a popular fiber for many products. In wearing apparel, the qualities of comfort, dyeability, and launderability have led to its wide use in clothing ranging from underwear to formal, evening gowns. Denim jeans are made of all cotton, or mostly cotton, fabric. Many home items such as sheets, towels, tablecloths, and napkins, draperies, and upholstery and slipcover fabrics are composed entirely or predominantly of cotton, and all-cotton items are often considered premium products.
 * Uses**

Cotton is often blended with other fibers--especially with manufactured ones. This blending may be done to create cottonlike fabrics with better wrinkle resistance and dimensional stability. More and more, cotton is blended with spandex to provide stretch for many apparel items. Various finishes developed for cotton can also compensate for less desirable qualities.

Cotton can be cleaned successfully using either detergents or natural soaps. The alkalinity of the detergents has no effect on the fiber. Dry cleaning solvents do not harm cotton, so where construction details or trim would make wet laundering undesirable, or when shrinkage is likely to occur, dry cleaning could be used.
 * Care Procedures**

Cotton's lack of resiliency causes significant wrinkling in laundering. Care labels may recommend that consumers dry knitted cotton items flat because when hung on clotheslines they may stretch and not recover their original shape.

Stains can be removed from white cotton using strong bleaches as long as water temperature, concentration of bleaching agent, and time of exposure are controlled. Strong chlorine bleaches should not be poured directly on cotton because pinholes can be formed in the fabric from direct contact with the bleach.

Footnote: All quoted or paraphrased from (Collier, Bide & Tortora, pp. 61-72).