| Abstract: | SUMMARIES. In many special exhibitions nowadays the visitor has to put up with dim lighting of 50 Ix and is told that this is necessary in order to protect the exhibits from overdue exposure to light. On the other hand, he is permitted to look at no less sensitive exhibits in the brightest daylight in rooms with overhead lighting, be it in older and new museums. Contradictions of this kind are due to inexact and incomplete recommendations on lighting. The art conservational aspects of the illumination of light-sensitive materials can, however, be explained in a rational and convincing manner. Systematic light protection is based on cause and effect which can be determined quantitatively. Thus the decision between illuminating an exhibit in a manner that is favourable to the visitor or in a manner that is acceptable from a conservational point of view no longer has to be based overall on the controversial lux values. Instead the decision can and should be made on the basis of the exposure threshold specific to the object at hand. There is a leeway within this threshold for suited degrees of brightness, however, perhaps to the detriment of the period of exposure. Finally, the decision comes down to the question at what point the inevitable changes that can be ascertained colourmetrically may become visible in a specific object; a question that can be answered by reflecting all museological aspects and assessing the specific exhibit. |
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