Author
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Chun, David |
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Submitted to: World Cotton Research Conference Proceedings
Publication Type: Proceedings Publication Acceptance Date: 5/4/2007 Publication Date: N/A Citation: N/A Interpretive Summary: Seed cotton moisture greatly influences ginning efficiency and usually seed cotton is dried to reduce moisture content because drier cotton is easier to gin and clean. The optimum moisture content of lint at the gin stand is probably between 5.0 and 8.5%, with the optimum range between 6.0 to 8.0% so that 7.0% lint moisture content is often taken as the average optimum most frequently used for efficient separation of lint from the seed. But because the classing systems offer premiums for better leaf grade, cotton is usually dried, cleaned, ginned, and packaged at moisture contents well below its eventual equilibrium moisture content in storage. To counter the resulting lower weight of excessively dry cottons, ginners sometimes resort to restoring some moisture, usually at the lint slide, to reduce bale-packaging forces and to recover the economic loss due to weight reduction resulting from drying. The temptation exists to add moisture to an excessive amount that may eventually adversely affect fiber quality. To this end, the Cotton Quality Research Station in Clemson, SC, has performed collaborative studies with various ginning laboratories to determine if the effects of moisture sprayed on fiber would affect lint quality, bale packaging and fiber quality during storage, and if there is a moisture range where the fiber quality would not be affected. Technical Abstract: Seed cotton moisture greatly influences ginning efficiency and usually seed cotton is dried to reduce moisture content because drier cotton is easier to gin and clean. The optimum moisture content of lint at the gin stand is probably between 5.0 and 8.5%, with the optimum range between 6.0 to 8.0% so that 7.0% lint moisture content is often taken as the average optimum most frequently used for efficient separation of lint from the seed. But because the classing systems offer premiums for better leaf grade, cotton is usually dried, cleaned, ginned, and packaged at moisture contents well below its eventual equilibrium moisture content in storage. To counter the resulting lower weight of excessively dry cottons, ginners sometimes resort to restoring some moisture, usually at the lint slide, to reduce bale-packaging forces and to recover the economic loss due to weight reduction resulting from drying. The temptation exists to add moisture to an excessive amount that may eventually adversely affect fiber quality. To this end, the Cotton Quality Research Station in Clemson, SC, has performed collaborative studies with various ginning laboratories to determine if the effects of moisture sprayed on fiber would affect lint quality, bale packaging and fiber quality during storage, and if there is a moisture range where the fiber quality would not be affected. Among the first of these studies, an excessive moisture range where the initial target moisture content was as high as 15% was used and the results indicated that after 116 days of storage that bales tended to be more yellow and darker as moisture content increased. In another study where cotton was stored for 6 months and the target moisture ranged from ambient moisture to 12%, the moisture content was found to be unevenly distributed in a bale, a direct relationship of moisture content with decreased reflectance and increased yellowness of the fiber over time, and increased fungal density with increased moisture content were observed. When lower maximum target moisture ranges were studied where the final moisture content after storage did not exceed about 7.5% moisture, the effect on fiber quality and microbial activity was minimal. Much of the results from these collaborative studies support the NCC Quality Taask Force recommendation that baled lint not to exceed 7.5%. |
