Light
Light, as a form of high-energy electromagnetic radiation, causes photochemical deterioration. Cumulative exposure to light causes colours to fade.
The two components of light which museums are concerned about are: visible light and ultraviolet (UV) radiation. Found in sunlight and invisible to the human eye, UV radiation is harmful to artefacts.
Notice the colour difference at the top, interior and the bottom due to exposure to light.The bright pink was not expoused as the lid of the basket acts as a shield.
The bright pink colour is being shielded from exposure to light by the lid.
This basket was one in a set of four, stacked one on top of another. Notice the parts that are pale and faded. Those were areas that have been previously exposed for prolonged periods to light.
Fading is an irreversible chemical reaction where high levels of radiation from sunlight or artificial light sources alter the chemical structure of light-sensitive pigments. Faded objects may look many shades lighter because of this change in the chemical and optical properties of pigment molecules.
While fading is caused mainly by light, seeing is not possible without light. To enhance the visitor’s experience and preserve the collections, museums use special lighting equipment that emits low UV radiation. Filters are also used to diffuse light where spotlights are used. At the same time, exposure time and luminance levels are lowered to suitable levels for the care of the artefacts.
