Leather

What are the most common types of damage?

Leather is also adversely affected by inappropriate environmental conditions and by biological pests.

Light and UV radiation affect leather in a number of ways, including:

• providing energy to the chemical breakdown of the collagen that makes up the leather;

• interaction with atmospheric pollutants, producing chemicals that damage leather and other materials associated with it;

• fading of dyes; and

• skin products with hair still attached often suffer hair loss through light-induced damage.

Extremes of relative humidity are damaging to leather. In low relative humidity conditions, leather dries out and can become hard, brittle and cracked. When the relative humidity is over 65%, leather is susceptible to mould attack. Leather is even more attractive to mould if it has been lubricated too much, because mould uses the ingredients of the lubricants as a food source.

Vegetable-tanned leathers, including items of harness, military equipment and bookbindings and upholstery, are susceptible to deterioration known as red rot, caused by pollutants in the atmosphere.

Dust is a major problem for leather objects because it can cause both chemical and mechanical damage. The sharp edges of minute particles are abrasive, and can cause fibre damage if removed by methods other than suction. Dust also attracts fungal spores, and acts as a centre for condensation and subsequent chemical attack.

Moulds, bacteria, rats, termites and many other insects attack leather and the materials incorporated in it.

Mould-damaged shoes. Photograph courtesy of the Western Australian Museum

The shoes have been treated to kill the mould and then cleaned. Photograph courtesy of the Western Australian Museum

Leather is often combined with other materials: metal buckles, for example. The interaction of these materials can be damaging.

Many fatty materials incorporated in leather dressings, react with metal components of leather objects, causing them to corrode. Evidence of this corrosion is often seen, for example, the presence of a turquoise, waxy substance on copper fastenings. Metals may have been incorporated into the leather from materials used during the manufacturing process. Deterioration caused by the presence of metals in the leather is hastened when relative humidity is high.