Museums
There are a number of important rules to observe when lighting museums. The first important rule is that no shadows should be cast on paintings or statues. It is vital that as one gets close to the works of art, the correct vision of these objects is not impaired by the shadows from the observer.
Artworks vary in their sensitivity to the harmful effects of light rays. Fabrics, watercolours and temperas should not be exposed to more than 50 lux. Oil paintings, frescoes and ivory should not be exposed to more than 150 lux. Stone, metal and ceramics should not be exposed to more than 300 lux.
Another important rule is that flat surfaces such as frescoes, paintings, tapestries and mosaics, should be lit up uniformly. On the other hand three-dimensional objects should not be lit up uniformly as the shape of the artwork can be better appreciated thanks to the play of light and shadow.
Glare is light scattered into the eye that shines on the retina and reduces the contrast of images that we would normally see clearly without the presence of glare. Direct glare is caused by light emitted by the general lighting fittings towards the observer. Indirect glare is caused by reflections of the emissions of the projectors pointed towards the art works. Indirect glare is most important to avoid for glossy surfaces as oil paintings or paintings covered with glass. The closer the light fitting is to the surface, the lower is the risk of reflection.
Another important factor to be taken into account is colour rendering, that is, choosing a light source that enhances the colours within the artwork. The colour hues of the work of art should be contained in the colour spectrum of the lamps used. A lamp with a colour tone closest to the prevalent colour within the artwork should be chosen. Thus where warm colours prevail, lamps with a colour temperature between 2500K and 3000K should be used as for example incandescent lamps. Where cold tones prevail lamps with a colour temperature between 5300K and 6000K should be used as for example florescent lamps.
