Exposure to light causes chemical reactions and stuctural breakdowns in organic materials. The visible light spectrum causes fading of certain dyes, bleaching of paper and colour changes in some organic pigments. The greatest damage is done by exposure to the ultra-violet light spectrum.

For valuable works of art , lighting must be controlled to minimise exposure to these risks.

Works of art under glass should be glazed with an ultra-violet filtering product.

The atmospheric temperature of the room where the artwork is to be stored or shown must be controlled, preferably between 20 º - 21º C.

With higher temperatures humidity rises and reactions increase.

Acids damage artworks by attacking their stucture internally, weakening their support and causing discolouration.

The main danger of excessive humidity is the encouragement of mould growth. Mould grows when humidity rises above 65%. Mould attacks the sizing in paper and weakens the sheet.

Low humidity causes the drying out of artworks and will cause embrittlement.

Most artworks should be stored with the humidity between 45 - 55%.

Many artworks are damaged by their own construction:
• Papers that have been poorly sized
• Artists using suspect pigments
• Poor choice of supports
• Poor surface preparation

When artists continue to use inferior products to make their works, the preservation of the artworks is a difficult process.

Physical damage through poor handling is an area where picture framers can help to minimise the damage to artworks.

Types of physical damage that occur through poor handling are:
• Abrasions
• Creases
• Tears
• Fingerprints
• Dents

The common insects that damage artworks are:
• Cockroaches
• Termites
• Woodworms
• Silverfish

Atmospheric pollution can cause fibre breakdown in paper and textiles. It can cause soiling and discolourisation of surfaces. A build up of surface dust traps moisture and promotes mould growth.

The common pollutants are:
• Sulphur dioxide
• Ozone
• Hydrogen sulphide
• Nitrogen oxides
• Dust