Cotton classing is the measuring and classification of cotton by its specific physical attributes. This information is attached to the individual bale and thus clarifies the actual value of it, helping the marketing for the cotton producers. For the consumer of cotton, i.e., the spinning mills, the precise information about the cotton fibers purchased, enables optimizing its raw material selection and blending, which is necessary for producing a continuous level of yarn quality.
Today, cotton is classed based on its measurements for fiber length, strength and length, micronaire (a measure of the cotton's fineness), color grade, color reflectance, color yellowness, and trash percent area.
In order to improve objectivity, cotton classing has largely moved from human senses (visual check by certified classers) to the utilization of high-volume, precision instruments which perform measurements of different parameters in a matter of seconds.
Cotton classing is usually organized by governmental agencies for the entire crop grown in their own countries. The first body to systematically conduct instrument-based classing is the United States Department of Agriculture (USDA), running a series of air-conditioned classification offices where the entire cotton crop is sampled and classified. Other countries running similar classification organizations are China, Australia, Uzbekistan, Brazil and Greece.
History
According to the USDA, an international group of cotton industry representatives met 1907 in Atlanta, Georgia to address serious problems that had developed in the marketing of cotton. A resolution was passed which recommended the establishment of uniform cotton standards to “eliminate price differences between markets, provide a means of settling disputes, make the farmer more cognizant of the value of his product, and, therefore, put him in a better bargaining position, and in general be of great benefit to the cotton trade.” In response to this and similar calls for action over the next several years, laws were passed authorizing the USDA to develop cotton grade standards and offer cotton classification services.
Since 1991, USDA cotton classification has applied an instrument-based classing process using the so-called High Volume Instrument (HVI) by Uster Technologies.