Previous official color standards for maple sirup, designated Light Amber, Medium Amber, and Dark Amber, were solutions of sugar caramel in glycerin standardized in terms of transmittance at 560 mμ. These solutions were not satisfactory because of instability of color and inconvenience of repeated preparation. Glass color standards were accordingly developed to match the chromaticities of fresh standard solutions in 31.5 mm depth. An improved color comparator was devised for use with the glass standards. The caramel-glycerin solutions and maple sirups were characterized spectrophotometrically and in terms of several one-dimensional color scales in use in the sugar industry. Complete specifications for the standard solutions and new glass standards are presented in the CIE system. Color tolerances were established in MacAdam units of chromaticity difference and a simple one-wavelength method of testing glasses for the production of duplicate standards was developed.
B. A. BRICE and ARTHUR TURNER, JR., "Glass Color Standards for Maple Sirup," J. Opt. Soc. Am. 46, 293-299 (1956)