May 25, 2016 at 5:47 pm #790
In general, all organic materials should be considered VERY LIGHT SENSITIVE or MODERATELY LIGHT SENSITIVE, and therefore susceptible to photochemical deterioration. Inorganic materials are generally NON-LIGHT SENSITIVE. These classifications are useful for assessing which items in your collection are more sensitive to light than others.
It is important to note that many items within a museum collection may be comprised of several different materials, such as a wooden dining chair with a fabric-covered seat. Such an item should be stored and displayed with the most light sensitive element (the textile seat) in mind.
The following materials are considered very susceptible to damage from visible light and UV radiation.
- Paper: this includes prints, drawings, watercolour paintings, stamps, books, manuscripts and wallpaper. The most susceptible are mass produced, cheap modern papers which are made from untreated wood pulp. These contain lignin, which breaks down to produce acids and yellow/brown substances, seen when newspaper is left in the sun.
- Watercolour pigments: many pigments are of plant or animal origin and tend to be more sensitive than others. (Many of these sensitive pigments are also present in oil paintings. As the pigment layer is usually thicker and the oil medium offers more protection, the effects can be less obvious).
- Fabrics: includes costumes, tapestries and other textiles
- Plant fibres: botanical specimens, and items such as baskets and tapas
- Animal parts: such as feathers, furs and skins
- Dyes and inks
The following materials are considered moderately light-sensitive.
- Oil or tempera paintings
- Undyed leather
- Lacquers and varnishes
The following materials are considered to be non-light sensitive.
Note again, that it is common for the items listed under the non-light sensitive category to incorporate a painted image, lacquer or varnish surface coating. Where these are present, remember to consider the entire item to be moderately sensitive to light.
May 25, 2016 at 5:48 pm #793
Light causes extreme and irreversible damage to many materials, most notably organic materials – those that derive from plants and animals. In a museum, this will include furniture, textiles, prints, books, drawings, manuscripts, wallpaper, dyes and inks, feathers and fur.
Generally speaking, all organic materials, that is, all things that originate from plants and animals are at greater risk of light damage than are inorganic materials such as stone, metal and ceramic objects.
You must be logged in to reply to this topic.