Lamps for Assessing Metamerism

Even if commercial products such as automobile paint and upholstery match in color and lightness under daylight illumination, they often mismatch under some of the many other common illuminants. Both paint and upholstery possess a spectral reflectance curve with a per cent of light reflected at each wavelength through the visible spectrum. Reflectance differences in certain particular wavelength regions are the troublemakers in such a mismatch. New fluorescent lamps emit in these wavelength regions. By causing about the worst possible mismatch, the new lamps give a dependable estimate of potential trouble with matching colors, and can indicate where the trouble lies. Conversely, prime-color fluorescent lamps have the peculiar capability of preserving a match prepared in daylight.