The role of botanical trash in the observed water content of ginned cotton has not been elucidated. Recently, a reference method for water content in raw and cleaned cottons based on Karl Fischer Titration was evaluated. The objective of this study was to compare – by modeling and Karl Fischer Titration – the water content in lint from two cultivars before and after mechanical cleaning with the Shirley analyzer. Models were developed as a function of the mass fraction of the aggregate trash removed in cleaning, and the water contents in the trash and cleaned cotton. Water content was also measured in the isolated trash after correction for entrained lint. The grand means in water content across both cultivars were : raw, 7.83%; after cleaning, 7.73%; and trash, 14.81%. Thus, the directly measured grand means difference in water content before and after cleaning was only 0.10%. This compared well with the predicted difference from modeling using the averaged mass fraction of isolated trash of 0.0135 from published work on six cottons. The water content in the trash particles was about twice that of the cleaned fibers; the mass fraction of trash was minute. Clearly, the mass fraction of impurities is the controlling factor in establishing the difference in water content before and after cleaning. Although only a limited number of cultivars were studied, these data suggest a decrease in water content of < 0.5% due to removal of botanical trash in screening studies from the bale to the yarn.
