Aboriginal and Torres Strait Islander Cultural Material

Mould on objects

Mould can be very damaging to a wide range of Aboriginal objects. It is disfiguring, can stain and obscure the surface, or even penetrate through the whole structure of an object.

Mould grows where the relative humidity is continuously above 65%, where there is stagnant air, and in dusty and acidic environments. Mould particularly affects wood-based objects which have not been thoroughly dried or seasoned before use.

Preventive action

It is important to seek the advice of a conservator before undertaking any action on a cultural object. In the case of bark paintings, it is particularly important if:

• painted surfaces are crumbly or powdery, and brushing the mould removes the paint; and

• the mould growth is ingrained into the surface of the object and the bloom is still visible.

As a preventive measure, spray the back of a bark painting or the unpainted areas of objects with Glen 10 or Glen 20. The object can then be moved to a drier and environmentally more stable area of the building.

Do building repairs, where necessary—to maintain the relative humidity below 65%.

Keep air circulating by using oscillating fans, which are more effective than ceiling fans.

Avoid placing objects in corners of rooms where there is minimal air circulation.

Inspect regularly for any signs of mould growth.

Maintain a clean room by vacuuming to prevent dust accumulation.

Avoid eating inside the room—foodstuffs are nutrients for mould as well as insects.

If you have a persistent mould problem, you may have to disinfect the room before your housekeeping efforts become effective. This means washing down the walls with a product such as Exit Mould, and disinfecting, clean surfaces with a Glen 20 or Glen 10 spray; Glen products have a residual effect for up to 3 months.

It is important to document the condition of the object before treating it. This can be a written description with an accompanying photograph. By examining the item thoroughly you will better understand the extent of the problem. For example, it is often found that mould grows initially from the back of a bark painting, where a hot, wet microclimate has developed, and the mould on the front is symptomatic of the greater problem on the back.

The method you use to clean mould from an object depends on the state of the mould. The treatment described below dries out and removes a light dusting of mould.

Place the mouldy item in a well-aired, stable atmosphere with relative humidity of 50-60%. This dries the mould so that it can be removed.

Drying the mould does not kill it. Unless it is removed outdoors or in a well-vented area away from the rest of the collection, the spores can spread, be deposited on other items and infect the rest of the collection.

Do not over-dry the environment. A significant drop in relative humidity can cause objects to warp, curl and crack. For example, don't place infected items in direct sunlight because this could cause them to split or warp.

Dried mould can be brushed off outside using a medium/stiff brush.

Where the mould has progressed to a thick growth and is damp to the touch, it is safer to remove it through a wet-cleaning process. This is particularly true for carved and painted wood sculptures where the paint is stable.

• Mix 7 parts industrial methylated spirits to 3 parts water in a small glass jar.

• Before you begin cleaning, test an inconspicuous area using a cotton swab.

• If there is no smudging of paint or colour loss, clean off the mould with damp swabs.

• Change swabs regularly.

• An alternative method is to dip a brush into the solution, brush the affected area with it, then remove mould residue with lint-free paper or fabric.

• Allow the object to air-dry naturally.