National Gallery Technical Bulletin Volume 11, 1987
David Saunders
Introduction
Since their introduction in the late 1930s fluorescent lamps have been widely accepted and have become a major method of lighting, particularly in offices, factories and public places. Economically, the fluorescent lamp presents an attractive alternative to, or replacement for, conventional tungsten incandescent lamps. For this reason art galleries and museums have investigated the possibility of employing fluorescent sources.
As an illuminant in circumstances where it is important to reproduce colour faithfully, fluorescent lamps are not without problems. These difficulties with colour-rendering and colour discrimination have been described in a previous volume of this ‘Bulletin’, which examined the various methods for determining theoretically the colour characteristics of light sources (note 1). As a result of this investigation certain colour-rendering criteria were proposed which were to be met by a light source before it could be considered as suitable for gallery lighting. Firstly, the general colour-rendering index (Ra) should be greater than 90, and secondly, the worst colour-rendering index (Rw) should be greater than 80. The derivation of these indices is explained in references (note 1) and (note 2).
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