Cotton classification system

The official cotton standards of the United States for the grade of Upland cotton are also called the universal standards. Leading cotton associations in major cotton-consuming countries meet periodically to establish a continuing consensus of cotton classification. International conferences are held every 3 years in the United States to consider revisions and to ensure accurate reproduction of the standards. By this method, the U.S. cotton classification system maintains sensitivity and responsiveness to cotton consumer needs. 

There are two methods for estimating fiber quality, expert appraisal by a trained classer, and instrumentation. Many different classification systems are used worldwide in the various countries where cotton is grown. For example, the United States [601], China [3,594,602], Uzbekistan [603], and Egypt [594] all have different systems. All systems measure cotton quality using similar parameters, even though the actual classification scheme and classification designations may be different. The determinations, either manually or by instrument, may be different for individual parameters also. The quality parameters are the following ... 

In the former Soviet Union [603], there were two classification systems. One was applied when supplying cotton to the domestic market and other socialist countries, the other for cotton sold to hard currency markets. The domestic system was GOST 3279-76. It had no scientific basis and could not estimate satisfactorily fiber characteristics for yarn production. The export version had no officially recognized physical standards. So a new system somewhat approaching the American system that could be used in international markets was developed. 

In 1993, a new classification system for cotton fiber quality, RST Uz 604-93, was introduced in Uzbekistan [603]. Since 1995, this standard has also been used in Kazakhstan and Tadjikistan [603]. In Azerbaijan, attempts are made to classify its cotton in accordance with international standards [605]. 

In Sudan [607], cotton is classified twice, as seed cotton before the gin and as lint at the port of shipment. The handpicked cotton is piled up on covers where trash and other contaminants are removed. Grades are assigned to the piles and the graded cotton is transported to the gin. The field classification system is felt to be key to implementing quality control measures such as timely and early picking, which can reduce stickiness. The ginned cotton is baled and transported to Port Sudan where the lint is reclassified and samples are taken for fiber testing. 

Classification by usage or appHcation is the principal system adopted by the Colour Index (5). Because the most important textile fibers are cotton (qv) and polyester, the most important dye types are those used for dyeing these two fibers, including polyester—cotton blends (see Fibers, polyester). 

This chapter is principally concerned with ligand systems which contain a carbon atom linked to two oxygen atoms. In the vast majority of the complexes to be considered the donor atom is the relatively small, less polarizable oxygen atom, i.e. hard under the Pearson classification. As a consequence these ligands are seldom found in conjunction with low oxidation state metals. Considerable advances have been made in this area in recent years. The most notable of these has been the work of Cotton, who has made extensive use of the ability of such ligands to bring metal... 

The U.S. HVI system for the classification of fiber quality and instrumentation for measuring other fiber properties are becoming more widely used all over the industrialized world, as well as in some developing countries for determining the proper laydown and mix for processing cotton in textile mills. Therefore, the U.S. system will be described in more detail than the other classing systems. Information also is given on how the various quality parameters can affect cotton fiber chemistry. 

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