Seed Fiber
Seed Fiber
Seed Fiber
(COTTON)
Mohammad Amir Hamzah Lecturer, Dept. of Textile Engineering PRIMEASIA UNIVERSITY Hamzah_031@yahoo.com
INTRODUCTION
The word cotton is derived from Arabic language, depending upon the Arabic dialect, it is pronounced as Kutan, Qutn, Qutun. Nomenclature: As the cotton fiber is obtained from the plant,
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As of 2007, the ten largest producers of cotton in the world are 1. PRC, 2. India, 3. the United States, 4. Pakistan, 5. Brazil, 6. Uzbekistan, 7. Turkey, 8. Greece, 9. Turkmenistan, and 10. Syria.
The five leading exporters of cotton in 2009 are 1. the United States, 2. India, 3. Uzbekistan/CIS, 4. Brazil, and 5. Australia.
The largest non-producing importers are Korea, Russia, Taiwan, Japan, Hong Kong and Bangladesh.
USA 19%
Turke y 5%
Uzbekista n 5%
South America 5%
Australia 4%
Western Europe 8%
Central Asia 9%
South America 6%
Australia 4%
CULTIVATION OF COTTON
Successful cultivation of cotton requires a long frost-free period, plenty of sunshine, and a moderate rainfall, usually from 600 to 1200 mm (24 to 48 inches). Soils usually need to be fairly heavy, although the level of nutrients does not need to be exceptional.
1. Soil: Cotton needs a soil with an excellent water holding capacity and aeration and good drainage as it cannot withstand excessive moisture and water logging. The major group of soil for cotton cultivation are the alluvial soils, black soils, and red sand loam. 2. Seed rate and spacing: Depending upon the variety, soil type, the cultivation on practices and method of sowing, seed rates and spacing have been recommended. A seed rate of 15 - 25 kg/ha and spacing of 75 - 90 cm between the rows are generally recommended for irrigated conditions. (1 ha = 10,000 sq.meter)
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3. Optimum sowing time: Sowing of crops depends upon water resources and varies
from region to region, usually mid April to mid May. Sowing in rows can be done
either by drilling, dibbling, or placing the seeds in furrows behind the ploughs. 4. Fertilizers: Fertilizer application differs from country to country depending upon available nutrients in the soil. For dry-land cotton crop, 20 kg of nitrogen, 18 kg of
conditions. Generally cotton crop needs 6 - 8 irrigations and 600 - 800 mm of water
during its lifetime. 6. Cultivation practices: Before sowing, the soil is ploughed, loosened and harrowed to make soil suitable for cultivation.
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A Cotton field
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7. Interculture: Weed control begins 30 - 40 days after sowing. Thinning of cotton is a special feature of the irrigated crop. 8. Diseases and pests: Cotton aphids, cotton jassids are controlled by spraying malathion 0.08%. Cotton leaf roller, spotted boll worm, pink boll worm are controlled by dusting crop with 10% carbonyl. 9. Optimum harvesting time: Cotton is harvested in three or more pickings taken suitable intervals. The season of harvesting varies with of sowing, duration of variety. Generally the crop is sown in June-September and in September-October is harvested from November to march to June respectively. Well dried bolls are picked either manually or through harvesters.
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An average boll will contain nearly 500,000 fibers of cotton and each plant may bear up to 100 bolls. In about 140 days after planting or 45 days after bolls appear, the cotton boll will begin to naturally split open along the bolls segments.
COTTON PICKING
Cotton is being picked up in two different and dissimilar ways; one is manual picking and the other is machine/mechanical picking. 1. Manual picking: Manual picking simply means hand picking. The main advantage of manual picking is that ripen and unripe cotton can be collected and separated easily. But the limitation is that lower productivity e.g. 100 lb/day/worker only. 2. Machine/mechanical picking: Speedy process thus higher productivity e.g. 600 lb/day/machine. Machine picking has got some limitations like- it picks leaves, stalk and sometimes dust, and it mixes ripen and unripe cottons those are difficult to separate later.
COTTON GINNING
Ginning is a mechanical process that aims to separate the cottonseeds from the cotton fibers. The role of the cotton gin has changed dramatically in the last 50 years to keep up with technological and production changes in the cotton industry. At one time, the gin's only function was to remove cottonseed from the fiber. Today, gins must not only separate the seed from the fiber, they must also dry and clean the fiber and package it into bales before it reaches the textile mill.
There are three different and dissimilar types for this purpose e.g. Saw gin, Roller gin and McCarthy gin. All gins differ in some aspects of the ginning process. In the Southwest, for instance, gins are equipped with both saw and roller gins: saw gins for ginning Upland cottons, and roller gins for ginning Pima cotton, a cotton grown almost exclusively in this region of the Cotton Belt (southern United States, where cotton is the predominant cash crop). Elsewhere in the Cotton Belt, gins use only saw gins in their operation.
Saw Gin
Parameters
Saw gin
Roller gin
McCarthy gin
Application
Components
roller.
Principle Fibers are separated from the seed by the help of case and air suction. Fibers are separated from the seed by the help of stripping board and grid.
knife.
Fibers are separated from the seed by the help of stripping board and grid.
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Parameters
Saw gin
Roller gin
McCarthy gin
Rotational
speed
400 lb/hour
30 lb/hour
Demerit
1. Sea Island Cotton: This is the highest quality and the most valuable of all commercial cotton fibers. It grows on the coast of the Gulf and Florida, in Barbados and other adjacent islands where the climates are favorable. The average length of this fibre is about 2 inch (51 mm) and the diameter is 1/1500 inch (0.0175 mm). It is famous for its uniformity, maturity, and highly developed luster, twist and softness. The color of this fiber is white to cream. 2. Egyptian Cotton: There are two kinds of Egyptian cotton; one is Brown and another is White. Like Sea Island cotton, this type of cotton is very regular i.e. uniformity is good and contains few immature or dead fibers. The average length of this fiber is 1.5 inch to 1.75 inch (38 44 mm), diameter is about 1/1500 inch (0.0175 mm). 3. South American Cotton: The cotton has a staple length of 1 inch to 1.5 inch (25 38 mm). It has a mean diameter of 1/1300 inch (0.0195 mm) and is suitable for
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4. North American Cotton: This type of cotton is cultivated in United States and
sometimes in Mexico. Its staple length is 0.9 inch 1.25 inch (23 32 mm) and the diameter is about 1/1200 inch (0.0211 mm). 5. Indian Cotton: This is short fiber cotton and the length ranges from 0.6 inch to 0.8
inch ( 13 20 mm).
6. Chinese Cotton: This is the lowest commercially accepted grade, length ranges from 0.5 inch to 0.7 inch (13 18 mm). Its twist is not highly developed and rather harsh. It is not suitable for spinning a good quality yarn and is usually used in a
now improving and lengths, color, maturity are fair to good. It is possible to produce
maximum 60s Ne yarn from Bangladeshi cotton.
Cotton is the seed hair of shrub plant which bears the botanical name GOSSYPIUM, a member of the Mallow family, cultivated as an annual plant. There are about 50 species of cotton plants however, only four of them have attained commercial importance. 1. Gossypium Barbadense: i. ii. iii. Plants are generally 6 15 ft. in height, yellow flowers. Fiber length ranges from 38 to102 mm. Sea Island, Egyptian cotton and American cotton belong to this class
2. Gossypium Harbaceum:
I.
II.
The plants are like bush and generally 3 6 ft. in height, yellow flowers.
Fiber length ranges 20 26 mm.
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3. Gossypium Hirsutum:
I.
II.
III. South and North American, also known as Upland or Mexican, cotton
yellow.
III. Originally South American cotton but Indian, Pakistani and Chinese cotton also belong to this class.
COMPOSITION OF COTTON
The chemical composition of cotton fibers and the quantity of different constituents vary greatly with the type of plant, soil and climate. Raw cotton fiber, after ginning, is
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Although cellulose is the chief component of plant cell-walls, as a naturally occurring material, it contains also a wide variety of other materials in small amounts notably protein, pectic substances, ash and waxy materials. These are frequently called fiber impurities, but they exert a considerable influence on the processing and usefulness of the fiber.
Ash: Cations, K+, Na+, Ca2+, Mg2+, Fe3+, Al3+, etc. Fat and Waxes: Cotton wax is found on the outer surface of the fiber. Cotton wax is primarily long chains of fatty acids and alcohols. The cotton wax serves as a protective barrier for the cotton fiber. Esters (based on C15 C33 fatty acids), Waxy alcohols (C24 C34), hydrocarbons, etc. Pectic substances: The pectic substances play an important role in plant life. The primary function of the pectic substances is the cementing together of the individual cells
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Proteins (also known as polypeptides): They are organic compounds made of amino acids arranged in a linear chain and folded into a globular form. The amino acids in a polymer chain are joined together by the peptide bonds between the carboxyl and amino groups of adjacent amino acid residues.
Organic acid and sugar: Organic acids are found in the cotton fiber as metabolic residues. They are made up of malic acid and citric acid. Sugar makes up point three percent of the cotton fiber, the sugar comes from two sources plant sugar and sugar
from insects. The plant sugars occur from the growth process of the cotton plant. The
plant sugars consist of monosaccharide, glucose and fructose. The insect sugars are mainly for whiteflies, the insect sugars can cause stickiness, which can lead to problems in the textile mills.
CELLULOSE
The existence of cellulose as the common material of plant cell-walls was first recognized by Anselm Payen, a French Chemist, in 1838. The chemical and physical properties of the cellulose fibers, their behaviour in dyeing and finishing as well as in practical demonstration is determined to a large extent by the cellulose portion. This is why it is possible to carry out the dyeing of the different cellulose fibers almost in the same manner. The constitution of cellulose The elemental analysis shows that cellulose contains 44.4 percent of carbon, 6.2
percent of hydrogen and 49.4 percent of oxygen. This corresponds to an empirical ratio
of six carbon to ten hydrogen to five oxygen and the simplest formula for cellulose is written (C6H10O5)n, where n is the polymerization factor i.e. DP.
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The d-glucose exists in two different modifications, i.e. in - and - form. The
distinction between these two forms arises from the position of hydroxyl ( OH) group on the C1 carbon. Alpha-glucose has an OH group that points downwards, away from the ring (on the opposite face to the CH2OH group), whereas the OH on carbon one of
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Definition Cellulose is an organic compound with the formula (C6H10O5)n, a polysaccharide consisting of a linear chain of several hundred to over nine thousand (14) linked dglucose units. It will be appreciated that natural cellulose is built up of glucose residues in this way:
H OH OH H H CH2OH
OH H H
OH H
HO
OH H
+ (n-1) H2O
O O
H
OH
H CH2OH
Glucose
Cellulose
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Where, n is the degree of polymerization (DP). The DP of cotton polymer is about 5000. One cellulose polymer may contain 10,000 glucose units.
Degree of polymerization (DP) The degree of polymerization, or DP, is the number of repeat units in an average polymer chain at time t in a polymerization reaction . The length is in monomer units. The
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The first step in this natural polymerization is the formation of one molecule of cellobiose from two molecules of glucose:
H OH OH H OH H
2
H
O
CH2OH
OH
Glucose
CH2OH H HO OH H H CH2OH H H H OH
OH
O O
H H H OH H
H2O
Cellobiose
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Cellulosic fibers: o Natural cellulosic fiber: Cotton, Jute, Flax, Hemp, etc. o Human made cellulosic fiber: Viscose rayon, Cuprammonium, Acetate, Triacetate, etc. Common properties of cellulosic fibers: High density, good absorbency, good conductivity of heat, low resiliency i.e. the ability to quickly recover any change, harmed by mineral acids, can withstand high temperature, attacked by mildew, burn in excessive application of heat and give feathery ash. Dye ability:
Direct, Reactive, Vat, Azoic, Mordant dyes are used to dye cotton fiber.
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Polymer system of cotton Cotton is a crystalline fiber. It consists of about 65 70% crystalline zone and corresponding 30 35% amorphous region. The repeating unit in the cotton polymer is cellobiose which consists of two glucose units. Its DP is about 5,000 10,000. It is about 5000 nm in length and about 0.8 nm thick. Functional groups in cotton: The most important chemical groups on the cotton polymer are hydroxyl groups (-OH), which are also present as methylol groups (-CH2OH). Their polarity gives rise to hydrogen bond between OH groups of adjacent cotton polymers. Less significant Van der Waals forces also occurs. Each glucose unit contains one primary hydroxyl group (as CH2OH) at C6 position and two secondary hydroxyl groups (as -OH) at C2 and C3 positions. Again one end of the glucose unit has an additional secondary hydroxyl group at C4 position and the other end has an aldihyde or hemi-acetal group at C1 position.
BY PRODUCTS OF COTTON
After picking, cotton is sent to gin where the seeds are separated and the fibers are pressed into the 500 poundal forces, ready for sale. The long fibers separated by ginning shall be used for textile manufacturing. These long fibers are called lint. The very short fibers (0.25 inch) remain with the seed are called linters and used in the manufacturing of human-made cellulosic/regenerated cellulosic fibers e.g. viscose rayon,
However, there are some by-products of cotton as below: o Seeds: Used in making oils and the residues are used in making soaps, glycerin, etc.. o Hulls: Used in making fertilizers and paper. o Linters: Used in rayon and acetate production, film and plastic production as well as in bank notes manufacturing. It is also used in making blanket, gauge and in
GRADING OF COTTON
In order to grade the quality of raw cotton, the rating is done according to the level of the length, strength, color, luster and impurities of the fibers. These are divided in different ways according to the production land.
Fibers are classified according to their quality. The classifcation of fibers is called grading. The grading is done basing on the following three factors: 1. Color 2. Foreign matters 3. Preparation of the fibers.
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On the basis of color: Color may be described in terms of three attributes namely hue, brilliance and chroma.
be extra white cotton contaminated with enough fine foreign matter, such as dust
to reduce it in the color scale. 3. Light Spotted: Cotton that has been discolored with light brown spots as a result of contact with wet bolls, leaves or stems.
4. Spotted: Cotton that has been discolored with brown spots as a result of contact
with wet bolls, leaves or stems. The brown discolorations are distinctly separated and in white cotton give a spotted appearance.
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5. Tinged: Cotton containing more extensive brown discoloration than spotted grades. The color is more uniformly distributed than in the spotted sample.
6. Yellow stained: Cotton is almost completely discolored and gives a spotty tan
appearance. Such stains are often difficult to remove during processing and consequently the grade is reduced.
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On the basis of foreign matter: The grade is based on the amount of foreign matter (polythene, ropes, etc. accumulated
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On the basis of fiber preparation: According to the quality of ginning/fiber preparation and gin damage, cotton is graded is below: American Cotton Middling Fair, MF Strict Good Middling, SGM Good Middling, GM Strict Middling, SM Middling, M Strict Low Middling, SLM Low Middling, LM Strict Good Ordinary, SGO Good Ordinary, GO Egyptian Cotton Extra Fine Fine Good Fully Good Fair Good Fair Indian Cotton Super Choice Choice Super Fine Fine Fully Good Good Fully Good Fair
FIBER MORPHOLOGY
Fiber Morphology is the study of the internal structure of fibers i.e. identification, analysis
The macro-structure of Cotton Under a microscope, a cotton fiber appears as a very fine, regular fiber, looking like a twisted ribbon or a
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because of these convolutions and kidney-shape, and thus makes the cotton fiber
fabric more comfortable to wear. Cotton fibers are amongst the finest in common use. They have a length from about 10 mm to 65 mm, depending upon the quality, and diameter is range from about 11 m to 22 m.
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The micro-structure of Cotton The cotton fiber is a single plant cell. Its cross-
Layer 1: The cuticle is a waxy protective layer that provides water resistance to the fibers as they are growing. This layer is removed by scouring during processing before spinning.
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Layer 4: The secondary wall is the last layer and it is actually made up of many layers of fibrils, each layer grows over a day and forms rings, kind of like a tree. The fibrils in the secondary wall are different in the way they grow, they do not really spiral, they change direction somewhat at random, making for a zig zag kind of formation. Weak
spots can occur in the spots where the fibrils change direction and the winding layer
helps compensate for this.
Layer 5: The lumen is not really a layer per say but rather the hallow tube that runs
through the center of the fiber. When the fibers are growing this tube is filled with fluid
(cell sap, proteins, sugars, etc.) but during processing it empties and collapses, which results in the flat appearance of the fibers and the kidney/bean appearance of cross sections of the fibers. The lumen is also part of what makes cotton so very absorbent.
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All these layers of fibrils make for a densely packed fibers. Also, as the fibrils layer around each other they make tons of microscopic capillaries, which also ups cottons absorbency. Cotton is a very hydrophilic (water loving) fiber and the cool thing about cotton fiber is when it is gets wet it swells and unlike a lot of other fibers (like silk or rayon) instead of getting weaker, it gets stronger. Now the question is, why? The best explanation is that when water molecules penetrate into the fiber, it lies between the fibrils and into the amorphous regions of the polymer. Where it forms hydrogen bonds with the free OH groups of the cellulose. This water absorption causes swelling of the secondary wall but little fiber elongation. Although absorbed water acts as a plasticizer, it also cements the cellulose chains and fibrils together by hydrogen bonding thus increasing the strength.
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All these layers of fibrils make for a densely packed fibers. Also, as the fibrils layer around each other they make tons of microscopic capillaries, which also ups cottons absorbency. Cotton is a very hydrophilic (water loving) fiber and the cool thing about cotton fiber is when it is gets wet it swells and unlike a lot of other fibers (like silk or rayon) instead of getting weaker, it gets stronger. Now the question is, why? The best explanation is that when water molecules penetrate into the fiber, it lies between the fibrils and into the amorphous regions of the polymer. Where it forms hydrogen bonds with the free OH groups of the cellulose. This water absorption causes swelling of the secondary wall but little fiber elongation. Although absorbed water acts as a plasticizer, it also cements the cellulose chains and fibrils together by hydrogen bonding thus increasing the strength.
CLASSIFICATION OF COTTON
1. Mature fiber: Well developed secondary cell wall and very small lumen size.
2. Immature fiber: Fibers with thinner secondary cell wall developed. They produce paler shade in dyeing due to their poor absorption capability of dyes. 3. Dead fiber: Only primary cell wall developed. They remain undyed in dyeing
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Commercial cotton may be classified broadly into following three classes in respect of
staple length: 1. Short staple: I. Length ranges from 3/8 inch to 1 inch.
II.
III. Medium strength and medium luster. IV. Indian and Asiatic cotton 2. Medium staple:
I.
II.
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3. Long staple: I. II. Length ranges from 1 inch to 2.5 inch. Diameter ranges from 10 to 15 microns.
Property
Evaluation
Fairly uniform in width, 12-20 micrometers; length varies Shape from 1 cm to 6 cm ( to 2 inches); typical length is 2.2 cm
to 3.2 cm (8 to 1 inches).
Luster Low
Tenacity (strength)
Dry Wet Resiliency Density 3.0 - 5.0 g/d 3.3 - 6.0 g/d Low. It refers to fibers ability to quickly recover from change . 1.54 - 1.56 g/cm
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Mercerized
Dimensional stability Resistance to: Acids Alkali Organic solvents Sunlight Microorganisms Insects
8.5 - 10.3%
Good
Damage, weaken fibers Resistant; no harmful effects High resistance to most Prolonged exposure weakens fibers. Mildew and rot-producing bacteria damage fibers. Silverfish damage fibers.
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CHEMICALLY COTTON
MODIFIED
2500C normal cotton loses one-third of its strength in three minutes, whereas PA cotton
loses one-third of its strength after twenty-five minutes at the same temperature. For this property, PA cotton can be used to make laundry press cover and give lasting for long time. It also withstands the attack of micro-organisms of mildew and rotting. It
has chemical resistance in 20% HCL, it loses only one-third of its strength after eight
hours, whereas ordinary cotton loses about two-thirds. It is a better electrical insulate. Uses: Sand bag, fishing nets and lines etc. where a high resistant to rot fabric is necessary.
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AM Cotton When cotton is treated with 2-amino ethyl sulphuric acid in NaOH, AM cotton is produced without changing its structure. Dyed AM cotton has better resistance to light
and washing.
Carboxymethylated (CM) Cotton Cotton treated with monochloro acetic acid and then NaOH is converted into CM
cotton. There are two types of CM cotton. One type of CM cotton has a starched
appearance and handle. It absorbs H2O more readily than cotton and can accept crease resisting treatments with greater effect. The second form of CM cotton can be produced easily in mercerizing equipment at very low cost. The product can be crease proofed
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Cayanoethylated (CN) Cotton Treatment of cotton with acrylonitrile yields chemically modified cotton described as cayanoethylated (CN) cotton. Though this looks and feel like ordinary cotton and many
of its properties are similar to that type of cotton, but CN cotton has extremely good
resistance to rotting influences. It has better resistance to the effect of heat than ordinary cotton. CN cotton dyes more readily than ordinary cotton with certain types of dyes.
Fox Fiber
Naturally colored cotton organically grown. During the 1990s color grown cotton was
back in production, due to the efforts of Sally Fox, an inventor from California, who cultivated long fiber colored cotton, and created her own patented cotton called "Fox Fibre". Naturally colored cotton is a naturally pigmented fiber that grows in shades of
Most Fox Fibre is grown organically (called Fox Fibre Colorganic), and requires minimal
processing because it does not need to be dyed. It is used in a wide variety of products today, including clothing, bedding and furniture.
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Organic cotton Organic cotton is a cotton that is grown without pesticides from plants which are not genetically modified. Though organic cotton has less environmental impact than conventional cotton, it costs more to produce.
What is the difference between natural cotton and organic cotton? Organic cotton is grown from non genetically modified seeds. And the farmer didn't use synthetic fertilizers or pesticides on the cotton crop.
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Organic cotton is grown around the world and must pass the same certification process. Farmers must verify that they used only acceptable methods and materials when growing organic cotton. A third party certification organization verifies that the cotton is organic.
How is organic cotton grown? Farmers use natural compost or manure in the place of chemicals. Harmful pesticides are replaced with organic friendly ladybugs. Instead of spraying chemicals on the cotton during harvest the fields are flooded to defoliate the
plants.
Any machinery used for harvesting organic cotton must be continually cleaned and sterilized. Any knitting machines that producers use must also be separate from other machinery. This prevents any other fibers or non organic crops from being combined
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Transition cotton Organic cotton must be grown in fields that have been
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Green cotton Green, or natural, cotton is not organic. When you see cotton products labeled "natural", you are getting conventional cotton grown with large inputs of chemicals, pesticides, and herbicides to control weed growth. The only difference between green and conventional cottons, is in the
processing: final product is not supposed to be treated with formaldehyde or chlorine bleach. Currently there are no federal inspection guidelines to ensure processing of green, or natural cotton, is chemical-free. It is important to understand this distinction when shopping for cotton products. Remember "natural" and "organic" are not at all the same.
Transgenic cotton Transgenic cotton, a genetically engineered cotton, carries its own insecticide within the
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