The gloss value of a test sample is determined relative to a standard, generally a polished piece of black glass. Therefore, gloss is a dimensionless quantity whose accurate determination requires standardized experimental conditions such as spectral distribution of the incident beam of light, incident and viewing angles; and a gloss standard. To help manufacturers monitor and assess specular gloss, the National Institute 7 of Standards and Technology (NIST) Physics Laboratory provides a special test service to calibrate. gloss reference standards. This facility is built around a newly rebuilt reference goniophotometer-an instrument that measures flux as a function of angles of illumination or observation-and a newly -developed primary gloss standard-three wedges of highly polished, high-quality optical glass. The system has an overall (k = 2) uncertainty of 0.4%. The new service offers calibration measurements of industry working gloss standards at the specular geometries of 20degrees, 60degrees, and 85degrees, in compliance with the International Standards Organization (ISO) 2813 and the American Society for Testing and Materials (ASTM) D 523 documentary standards. This article describes a bilateral comparison of specular gloss scales between NIST and the National Research Council of Canada (NRCC) that has been performed. The results of this comparison show agreement within the combined uncertainties for the measurement of specular gloss of highly polished black glass.
Citation: JCT, Journal of Coatings Technology
Issue: No. 943
Pub Type: Journals
color, gonioapparent coatings, reflectance colorimetry, standards