FEASIBILITY of “TRACEABLE” COLOR STANDARDS for COTTON COLOR

Authors: Rodgers Iii, James; Thibodeaux, Devron; Campbell, Jacqueline; Cui, Xiaoliang

Submitted to: American Association of Textile Chemists and Colorists Review
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/2008
Publication Date: 1/1/2009
Citation: Rodgers III, J.E., Thibodeaux, D.P., Campbell, J.H., Cui, X. 2009. FEASIBILITY of “TRACEABLE” COLOR STANDARDS for COTTON COLOR. American Association of Textile Chemists and Colorists Review. 9(1):42-47.

Interpretive Summary: Cotton color is measured on the Uster® High Volume Instrument (HVI) for Rd (diffuse reflectance) and +b (yellowness). Rd and +b are cotton-specific color parameters, and they are not as well known as other globally recognized color systems (e.g., L*a*b*). For L*a*b*, L* is how light or dark a sample is; a* is how red or green a sample is; and b* is how yellow or blue a sample is. Further, the HVI color standards are do not have “NIST-like” traceability or means to verify/certify these standards. A comparative program was implemented to investigate new standard procedures and protocols, to evaluate globally recognized color systems (e.g., L*a*b*), and to investigate the possibility for “traceable” or verified/certified HVI color standards by AMS. Samples were measured on both bench-top and portable spectrophotometers from five manufacturers. Good to excellent color unit agreement was observed for the tiles when glass is not used in the measurement, but only fair agreement was observed for all units when glass is used (glass placed between the sample and the spectrophotometer port). The primary variable that impacted the color results was the use of glass. The color results indicate that the development and use of “traceable” or verified/certified color standards for HVI and color spectrophotometer color measurements is feasible. The most promising standard system is the use of ceramic or metal tiles with no glass used in the color measurement, preferably with a bench-top color sphere spectrophotometer to minimize geometry differences between the color units.

Technical Abstract: Cotton color is measured on the Uster® High Volume Instrument (HVI) for Rd (diffuse reflectance) and +b (yellowness). Rd and +b are cotton-specific color parameters, and they are not as well known as other globally recognized color systems (e.g., L*a*b*). Further, the standards used for HVI color are ceramic tiles and cotton batts, but there is no “NIST-like” traceability or means to verify/certify these standards. A comparative program was implemented to investigate new standard procedures and protocols, to evaluate globally recognized color systems (e.g., L*a*b*), and to investigate the possibility for “traceable” or verified/certified HVI color standards by AMS. The color tile, AMS standard tile, and AMS standard cotton batt/fiber samples were measured on both bench-top and portable spectrophotometers from five manufacturers. Good to excellent color unit agreement was observed for the color tiles and AMS tiles when glass is not used in the measurement, but only fair agreement was observed for all units when glass is used (glass placed between the sample and the spectrophotometer port). The primary variable that impacted the color results and inter-instrument color unit agreement was the use of glass. The use of glass resulted in a large decrease in reflectance (%R), which decreased L* significantly and a* and b* to a much lesser extent. The inter-instrument color results indicate that the development and use of “traceable” or verified/certified color standards for HVI and color spectrophotometer color measurements is feasible. The most promising standard system is the use of ceramic or metal tiles with no glass used in the color measurement, preferably with a bench-top color sphere spectrophotometer to minimize geometry differences between the color units.