Publication Sponsored by the Society's Colour Measurement Committee — XIV The Impact of Modern Lighting on the Dyer

Until recently, the two desirable characteristics of high lamp efficacy and good colour rendering were mutually exclusive in fluorescent lamps but in 1971 calculations were made which showed that they could co‐exist if the emitted light approached a 3‐line spectral power distribution (SPD), ideally the emission bands being at 450, 540 and 610 nm. The discovery of new phosphors has made such lamps a practical possibility and two manufacturers have marketed lamps whose SPDs lie between the continuous SPD of conventional lamps and the 3‐line ideal. Such lamps have been found to render many objects more colourful than any conventional lamps and thus more acceptable to the average observer. This combination of desirable characteristics suggests that such lamps may become the most common form of artificial lighting, especially in view of the need to conserve fossil fuels. Tire installation of one of these lamps in a large department store, however, caused some serious problems with textiles which were metameric matches. These may be more serious with sources whose SPDs are closer to the 3‐line ideal. The same problems will also occur with nontextile materials, e.g. ceramics and plastics, which match under various conventional sources. These developments in lighting may make extensive re‐matching necessary.