The new official United States color standards for grading gum rosin are described and compared with the superseded 1923 Lovibond glass standards. The new standards are made of cemented combinations of Jena and Corning glasses, and show a better spectral match with rosin, higher luminous transmission, more regular spacing of colors on a chromaticity scale, and are more solidly constructed than the old standards. Spectral transmission curves for rosins and the glass standards are shown. The standard colors are specified in terms of the 1931 I.C.I. colorimetric coordinate system with its standard observer and standard illuminant C. Chromaticity tolerances are established for duplicate standards.
BROOKS A. BRICE, "The United States Color Standards for Rosin," J. Opt. Soc. Am. 30, 152-158 (1940)