Field Evaluation of Color/Trash Meters

Two laboratory-type video color/trash meters were installed and evaluated in a commercial gin during the 1989 and 1990 ginning seasons. Calibration of the meters was accomplished using manufacturer-supplied reference standards. During the 12-week ginning season each year, in which about 18,000 bales were ginned, the meters performed without any maintenance problems. Samples were collected from the cotton during gin processing throughout the ginning seasons in order to verify the accuracy of the meters. Comparison of measurements made by the meters during ginning to those made on representa-tive samples by the USDA, Agricultural Marketing Service, Cotton Division produced acceptable repeatabilities 72%, 49%, and 79% of the time for trash, reflectance (Rd), and yellowness (plus b), respectively. Acceptable values for similar measurements with two laboratory meters were 75%, 81%, and 75%. Thus, reflectance measurements had a lower repeatability for the gin measurements than for the laboratory measurements. If twice the allowable laboratory deviations are assumed to be acceptable for gin process control, then the repeatability percentages increase to 84%, 73%, and 87% for trash, reflectance, and yellowness, respectively. Color grades, which are a combination of reflectance and plus b measurements, were estimated correctly about 55% of the time, whereas 94% were estimated correctly within one grade. Video color/trash meters can be utilized in commercial ginning systems to estimate the color and trash components of cotton.