Light plays an essential role in the exhibition of artifacts and works of art. Without light, nothing can be seen and changes in the quality of light can drastically alter the color rendition of objects. Unfortunately, it can also cause the deterioration of materials. The fading of pigments and dyes is one example. To go into detailed explanation of the nature of light would be defeating our purpose of presenting practical information for museum personnel. A very general and brief explanation will suffice. Visible light is only a small part of a series of radiations which make up the electromagnetic spectrum. ... Visible light is that part of the spectrum between 400 nm to 700 nm; ultraviolet radiation starts at 400 nm, and infrared is beyond 700 nm. Both visible light and ultraviolet radiation can cause photochemical deterioration. Fortunately, ordinary glass will absorb radiation below 300 nm so that museum objects will not be subjected to the most damaging rays. Nevertheless, radiation between 300 and 400 nm must be excluded since it may be damaging to the object. Since we cannot exclude visible light completely, it is necessary to carefully control it intensity.
