Think of light as refracted through a prism. The segments of the spectrum from the green down through the blue and violet also cause photochemical deterioration. Heat build-up causes dimensional change and stress, accelerates chemical reactions, and softens finishes such as wax and varnish. Considering the litany of damage above, control of light in the museum environment may seem hopelessly depressing. Nonetheless, some basic information and procedures can decrease light damage enormously.
Daylight is the most dangerous light source because it is the most intense.
On a sunny day, daylight is 200 times more intense than the illumination from artificial lights in a well-lit room. Fluorescent light is a concern because it yields high amounts of ultraviolet light in comparison to other artificial light sources. The most immediate danger of incandescent light is heat build-up. First and foremost, beware of daylight. Direct sunlight is the worst culprit, but even northlight or daylight filtered through ultraviolet shields will cause more photochemical deterioration than unshielded fluorescent lights.