Title: Storage of Cotton Bales at Marginal Moisture Levels Authors
|McAlister Iii, David|
Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: December 9, 2004
Publication Date: January 7, 2005
Citation: Anthony, W.S., Mcalister Iii, D.D. 2005. Storage of cotton bales at marginal moisture levels. National Cotton Council Beltwide Cotton Conference. CD ROM pp. 694-708. Interpretive Summary: Increased use of direct-spray water application after ginning and before bale packaging has caused problems throughout the cotton industry, especially in cases where too much water was applied. Previous studies clearly indicated loss of color grade during storage at moisture contents above 8% and suggested problems at lower moistures; however, the precise maximum limit for moisture has not been established. When too much water is added, the color grade and weight of the bale when it arrives at the textile mill is lower than it was at ginning, creating an integrity problem. The purpose of this study was to determine the impact of excess water in cotton bales at levels from 5 to 9% moisture content. The study involved 48 bales of cotton from six different modules of seed cotton with several different moisture restoration regimes applied. Bales were ginned at a commercial gin and the amount of water added per bale ranged from 0 to 20 lbs. Initial moisture contents ranged from 4.6% to 8.1% and final bale moisture contents ranged from 6.5% to 7.3%. Minor changes in color grade (grayness and yellowness) occurred until moisture contents reached about 7.3%, and then the grayness changed substantially. This test clearly showed the negative effect of low levels of moisture sprayed directly on the fiber immediately before bale packaging, beginning at about 7% moisture content. Use of these results will maintain both cotton color and bale weight, and improve the acceptance of bale weights and grades for cotton established at ginning.
Technical Abstract: Previous studies clearly indicate that water droplets sprayed directly on cotton fiber at the lint slide cause color change and weight loss during storage. This report describes research to determine the impact of moisture added by the humidified air and direct spray approach to cotton bales at a commercial gin. The study involved 48 bales of cotton from six different modules of seed cotton with several different moisture restoration regimes applied. The regimes included 1) humidified air, 2) direct spray, and 3) combination of one and two. Generally the test sequence was as follows: 1) gin one module for practice, 2) gin the first bale of the test module for practice or warm-up, 3) apply one of the three treatments on two consecutive bales, 4) process two practice bales to adjust for the next restoration condition, and 5) continue with next treatment. A standard ginning sequence for the cotton including two driers, two cylinder cleaners, one stick machine, extractor-feeder, gin stand, and one lint cleaner was used. Two driers at 200 ºF were used on the low moisture treatments; one drier at 100 ºF was used on all the high moisture treatments. A strip-laminated, woven-polypropylene, bagging was used on all bales. The amount of water added per bale ranged from 0 to 4% for the bales. The bales were weighed on 8 occasions, beginning with immediately after packaging. The bales generally lost weight initially and then gained weight. The class data after moisture restoration was subtracted from the class data before the moisture restoration for each factor and the difference between the means was zero in all cases. The bales were then shipped to Clemson for opening and subsequent moisture analyses and HVI testing. Average bale moistures at Clemson ranged from 6.5% to 7.3% and back-calculated moistures based on weight change to estimate the actual moisture before storage ranged from 4.6% to 8.1%. Minor changes in Rd and +b occurred until moistures reached about 7.3%, then the Rd changed substantially. This test clearly showed the negative effect of low levels of moisture, beginning at about 7% moisture content.