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United States Department of Agriculture

Agricultural Research Service

Research Project: New and Improved Assessments of Cotton Quality

Location: Cotton Structure and Quality Research

Title: Fiber sample presentation system for spectrophotometer cotton fiber color measurements

Authors
item Rodgers, James
item Elkholy, Karim
item Cui, Xiaoliang
item Delhom, Christopher
item Fortier, Chanel

Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 5, 2012
Publication Date: April 30, 2012
Citation: Rodgers III, J.E., Elkholy, K.N., Cui, X., Delhom, C.D., Fortier, C.A. 2012. Fiber sample presentation system for spectrophotometer cotton fiber color measurements. Journal of Cotton Science. 16(2):117-124.

Interpretive Summary: The Uster® High Volume Instrument (HVI) is used to assess the quality U.S. cotton for fiber color, yielding the cotton-specific color parameters Rd and +b. The HVI examines a 9 square inch fiber sample, and it is also used to test large AMS standard cotton “biscuits” or rectangles. Much interest has been shown in measuring cotton color on modern color spectrophotometers and on relating the HVI Rd and +b color parameters to more globally recognized, 3-dimensional color space systems obtained from spectrophotometers, such as CIELAB or L*a*b*. Recent research has demonstrated and validated the relationships of Rd and +b to L*a*b*. However, concerns have been expressed on the pressure consistency of fiber measurement with large volumes of cotton fiber on spectrophotometers. When cotton fiber is measured for color on color spectrophotometers, hand pressure by an operator is often used to hold the fiber against the spectrophotometer sampling port for the color measurement, but the pressure applied varies from operator to operator and from sample to sample. A program was implemented to develop a pressurized fiber sampling system for color measurements with large cotton fiber samples (e.g., AMS standard cotton biscuits) so that uniform pressure could be applied to the large area samples. A sampling system for large cotton fiber samples was developed for color spectrophotometers. The color parameter most impacted by fiber pressure was L*. Protocols were developed for pressurized cotton fiber color measurements on spectrophotometers.

Technical Abstract: The Uster® High Volume Instrument (HVI) is used to class U.S. cotton for fiber color, yielding the industry accepted, cotton-specific color parameters Rd and +b. The HVI examines a 9 square inch fiber sample, and it is also used to test large AMS standard cotton “biscuits” or rectangles. Much interest has been shown in measuring cotton color on modern color spectrophotometers and on relating the HVI Rd and +b color parameters to more globally recognized, 3-dimensional color space systems obtained from spectrophotometers, such as CIELAB or L*a*b*. Recent research has demonstrated and validated the relationships of Rd and +b to L*a*b*. However, concerns have been expressed on the consistency of fiber sampling/measurement of large volumes of cotton fiber on spectrophotometers. When cotton fiber is measured for color on color spectrophotometers, hand pressure by an operator is often used to hold the fiber against the spectrophotometer sampling port for the color measurement, but the pressure applied varies from operator to operator and from sample to sample. The need exists for a spectrophotometer fiber sampling system for large area fiber samples that allows for the application of uniform pressure to large areas of cotton fiber samples. A program was implemented to develop a pressurized fiber sampling system for color measurements with large cotton fiber samples (e.g., AMS standard cotton “biscuits”). A sampling system for large cotton fiber samples was developed for color spectrophotometers, in which a uniform pressure is applied across the entire large area sample. The color parameter most impacted by fiber pressure was L*. Protocols were developed for pressurized cotton fiber color measurements on spectrophotometers.

Last Modified: 4/20/2014
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