Automatic measurement of particulate contaminants (dirts) in cotton linters

An electronic image scanning measurement method was developed to obtain objective measurements of the area of resistant dark contaminants, broadly referred to as dirts, contained in cottonseed linters and hull fibers. The method is based upon the use of the AOCS standard cellulose yield residue. The yield residue (20 g) was bleached and formed into a 10 × 12 in. test sheet, and the projected area of visible dirts in 42 fields on each side of the sheet was meausred. Areas as small as 0.1 mm 2 in a field 30 × 41 mm can be measured. The results were converted to area, summed, and compared with the visual measurements obtained using the method of Jurbergs and Dowling. Statistical analysis gave standard deviations of ca. 8% and 25%, respectively, for new and the earlier procedures. The instrument standard deviation was shown to be ca. 1% relative. A comparison of the two methods using samples of 1099 different lots of linters gave a 0.94 correlation coefficient.