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Tests were conducted using a rotor spray system to apply moisture in the form of fine water droplets to cotton lint at the lint slide just before bale packaging. Two studies were conducted, one in which bales were stored for 6 months and another in which bales were stored for 15 months. For the first study, initial cotton lint moisture content averaged 5.1% and ranged from 4.4% to 5.7%, wet basis, and for the second study the initial moisture content averaged 5.5% and ranged from 5.1% to 5.9%. For the 6-month storage test, five levels of moisture addition were studied, including average moisture levels of 6.3%, 6.5%, 7.0%, 7.7%, and 7.9% moisture (just after rewetting), in addition to bales with no additional moisture added. For the 15-month storage test, three levels of moisture addition were studied, including 8.0%, 8.4%, and 10.0% moisture (just after rewetting). In both studies, cotton quality degradation was determined after each of the respective storage periods. No significant changes were found in HVI micronaire, strength, length, or uniformity or any properties measured with the Advanced Fiber Information System. At moistures of 7.5% and greater, the color +b value decreased slightly and the decrease was statistically significant. When considering the moisture range used in this study, results are consistent with earlier studies using atomizing spray nozzles, therefore recommendations for using a rotor spray system for adding moisture to cotton fiber at the lint slide should be the same as those for using an atomizing spray nozzle system. Thus, in order to minimize color degradation during storage, cotton lint moisture should be less than 7.5% wet basis (8.0% dry basis) when the bale is formed.

The study of the addition of water to cotton at ginning dates back to the early 1950s. Since that time, technologies have changed, allowing for more control and higher volumes of water to be added to cotton at the lint slide than ever before. The objective of this study was to determine an acceptable bale moisture range within which fiber quality, yarn quality, and dyed fabric quality degradation can safely be avoided after six months of bale storage. Approximately 22.7 kg (50 lbs) of cotton were sampled from each of the three bales for each of the four moisture treatments after six months in storage. In addition to the HVI fiber properties, additional testing of the fibers was performed on the Advanced Fiber Information System (AFIS), as well as a microbial assay to determine any microbial damage to the cotton during storage. The resulting 20/1 open-end spun yarns were subjected to typical yarn quality measurements (C.V., defects, strength, and elongation) and then circular-knit into panels so that yarn from each treatment was butt-knit to more easily observe color or shade change. HVI data indicated that the moisture treatment levels and storage period had an adverse impact on color Rd and +b with increasing amounts of water added at the lint slide. Although microbial data were collected, the data did not indicate any significant activity during the six months of storage. As for yarn quality, it appears that 9.1 kg (20 lbs) or more of water added to bales of cotton at the lint slide resulted in significant as well as practical reductions in yarn quality. With respect to the six-month storage period and the treatments used in this study, although there were color changes to the cotton fiber, there appeared to be no impact on the bleached and dyed fabric. Additionally, it appears that the point of diminishing return for adding moisture to cotton at the lint slide lies between 6% and 8.5%.