Portable Color Spectrophotometer Measurements of Cotton Color in Remote Locations

The Uster ® High Volume Instrument (HVI ®) is used in the U.S. to classify cotton, including cotton color. The cotton color parameters measured on the HVI are Rd (diffuse reflectance) and +b (yellow-ness). Comments from industry have indicated that some cotton bales appeared to have changed significantly in +b (yellowness) from their initial HVI color measurements. As a result of these reports, there was interest in " on-site " /remote location measurements of cotton color that will yield " real time " color values, with emphasis on yellowness. A program was implemented to develop portable color spectrophotometer procedures and protocols to perform rapid, precise, and accurate cotton fiber ™ software. AMS standard tiles, cotton samples, and routine cotton samples were used to perform comparative evaluations to establish the relationships between the HVI Rd and +b and portable spectrophotometer L*a*b* color parameters. The best correlations were achieved between 1) the HVI +b and portable spectrophotometer b* and 2) the HVI Rd and spectrophotometer Y. Excellent comparative results were obtained and all end-state criteria were achieved (high R 2 s, low spectrophotometer analytical variability, and a low number of outliers). The HunterLab MiniScan EZ (MSEZ) results were interfaced with the EFS System MILLNet ™ software, and preliminary field trials were performed on more than 400 bale samples at a non-U.S.-based mill. Very good color agreement was observed between the mill's HVI unit and the MSEZ-MILLNet ™ system, with distinct and significant +b color shifts detected. T he use of high speed and high volume instrumentation to measure, class, and determine the quality of cotton is rapidly becoming a global practice. Color is an important quality parameter for cotton fiber, and it is most often obtained in the U.S. during fiber classing with the Uster ® High Volume Instrument (HVI ®) (USDA-AMS, 2005). The HVI unit contains a two-filter colorimeter (two regions of the visible spectrum). The fiber color parameters obtained with the HVI unit are Rd (diffuse reflectance) and +b (yellowness). During HVI color measurement, the fiber sample is placed against a glass window, and the color is measured through the glass (~6 mm thick). Cotton is a global commodity, and it is normal for some color change to occur in cotton over the time bales are stored before being used. In the U.S., cotton properties of the bale are tested by the U.S. Department of Agriculture (USDA) soon after ginning, …