Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: December 20, 2007
Publication Date: July 1, 2008
Citation: Byler, R.K. 2008. Bale Bagging Effect on Bale Weight Change During Storage: Measured and Modeled. National Cotton Council Beltwide Cotton Conference. Nashville, TN. CD ROM pp 766-777. Interpretive Summary: Cotton bales are formed at gins, usually with relatively dry cotton lint, and stored until needed by mills. Traditionally the bales were covered by a permeable covering and stored in a humid environment so that the lint took up moisture from the air. This resulted in a gain in weight and an increase in fiber strength. More recently cotton bagging has been made from plastic materials which are much less permeable because they protect the bales well, are lighter in weight, and are less expansive. In this study cotton was dried, ginned, formed into bales, placed in different types of bagging, and stored for over 3 months in a room with constant temperature and high and constant relative humidity. The bales were weighed periodically and the change in weight modeled mathematically. Different bales with the same type of bagging resulted in similar models, as expected. A half-time to moisture equilibrium was calculated from the models which ranged from 10 to 102 days. This analysis provided a simple number related to moisture permeability of the bagging materials and allowed them to be ranked based on the bale weight change. The half-time allows ranking bale bagging for those concerned with the rate of change of bale weight during storage. The number communicates in a simple way a rather complicated process which will allow better communication among those concerned with cotton bale weight changes during storage.
Technical Abstract: Universal Density cotton bales were formed with relatively dry lint, covered with different types of cotton bale bagging materials, and the bales stored in a humid environment for more than 3 months. The bale coverings included coated woven polypropylene with and without holes, linear low density polyethylene film with different hole patterns, and no bale bagging. The bales were weighed periodically during storage. Some bales were then exposed to drier conditions and the weight change over time again recorded. The bale weight changes were modeled with a single term decaying exponential. Different bales in the same bagging type changed weight consistent with the models. The rate of bale weight change from the models was used to calculate a half-time to equilibrium, in days, for each bagging type. The half-time for bales with no bagging was 10 days, for bales in coated woven polypropylene bagging with holes punched in it was 34 days, and for bales with an experimental bagging made of polyethylene film with small holes was 102 days. This half-time number will allow simplified communication of the effect bale bagging has on the rate of change of cotton bale weight during storage.