This article explores the historical relationship between scientific research and labor management by investigating the state supervision of color perception in British workers (1870s-1920s). Whereas eighteenth-century scientific writers had described color blindness as an individual idiosyncrasy, color blindness was interpreted in the late nineteenth century as a social contaminant. As multiple sites of labor and industry were saturated with color—for example, through the deployment of flashing red and green lights on ships and railways—the color vision of workers became an increasingly significant medical and legal concern. Starting in the 1890s, the Board of Trade developed new efforts to legislate the admittedly subjective realm of color perception. But British workers also publicly opposed the Board's efforts to regulate their perception and objected to the “modernist” palette that was commonly used in color vision tests. I trace the emergence of color blindness as a class-specific pathology and consider both the denigration and the valorization of workers' perceptions in modern British industrial society.