According to the cotton varieties, and the length and thickness of the cotton fiber produced, cotton can be divided into three categories of fine cashmere cotton, long cashmere cotton and coarse cashmere cotton: fine cashmere cotton: refers to various varieties of cotton on land. Its characteristics seed cotton cotton flap fat and fluffy, fiber soft and elastic; The color is fine white, white, or opal white, fine bright and mercerized. Fiber is fine and long, the length is generally 25-32mm, fineness 5000-6500m/g, single fiber strength 3-4.5gf. Long staple cotton: refers to various varieties of island cotton and sea and land hybrid cotton. The seed cotton flap of this product is fluffy, and some of it has wrinkles. The fiber is slender and soft, good quality; Color white, milky or light yellow, with mercerization. The fiber length is generally 33mm and above, the fineness is 7000-8500m/g, and the single fiber strength is 4-5gf. Coarse cotton: refers to the varieties of cotton (Asian cotton) and grass cotton (African cotton or small cotton). The cotton flap is compact and small in shape. Fiber short elastic, white or dull white, slightly mercerized. The length is generally below 23mm, the fineness is below 4000m/g, and the single fiber strength is 6.5-7.5gf.
       The same type of cotton fiber can be divided into the following types according to some characteristics. Long staple cotton can be divided into two types according to the fiber length and economic value of extra long staple cotton and medium long staple cotton: extra long staple cotton fiber length of 35mm or more. Medium long staple cotton fiber length in 33-35mm long staple cotton Fine staple cotton usually according to fiber color, processing methods and other characteristics of the different there are three types: a, white cotton type: normal mature cotton fiber is white or milky white for white cotton. b, yellow cotton type: cotton growth period due to frost or other reasons. The cotton fibers are yellowish-white. c, gray cotton type: cotton fiber due to wind and rain, mold invasion, cotton fiber is gray.
Third, the abnormal fibers formed by the special reasons for the division of other cotton types are mainly:

 (1) Sterile seed recovery cotton: long fibers recovered from the sterile seeds discharged by the saw gin. 

 (2) Water-soaked cotton: After the cotton fiber is soaked in water, the waxy layer on the surface of the fiber is destroyed, and the fiber is brown.

 (3) Fire cotton: damaged by fire, burnt cotton fiber 

 (4) Oil cotton: in the process of ginning, stained with oil cotton fiber. 

 (5) Floor cotton: in the process of acquisition, processing, packaging, transportation, storage, etc., falling on the ground sticky dust, weeds, leaves and other impurities, good mixing, more impurities of cotton fibers.


The cotton fiber is formed by the elongation and thickening of the epidermal cells of the ovule (the coming cotton seed), so that one cell grows into a fiber, one end of which is on the surface of the seed and the other end is closed. The formation process of cotton fiber can be divided into three periods: the elongation period of fiber, the thickening period of fiber secondary layer, and the dewatering and bending period of fiber.