Aboriginal and Torres Strait Islander Cultural Material

Care of wooden objects

In the Top End, many wooden objects—particularly carvings-are made from the soft wood of the Beach Hibiscus—Hibiscus tiliaceus—the Kapok Tree—Bombax cebia—Shitwood—Cyrocarpus americans—the Milkwood—Alstonia actinophylla-acacias and eucalyptus woods.

Burial poles and weaponry on Melville and Bathurst Islands are commonly made from Ironwood—Erythophleum chlorostachys—or Bloodwood—Eucalyptus nesophila.

Most items are made from freshly cut timber, that has been dried for several days, though this varies according to the maker. On Melville and Bathurst Islands, burial poles are made, where possible, from fallen logs which are already cured through a long drying out period.

In arid central Australia, the most common wood used for making weapons and carvings is Mulga wood—Acacia aaneura. Other commonly used timbers for making artefacts are Bloodwood-Eucalyptus opaca—Desert Kurrajong—Branchyiton gregorii, and Sandhill Wattl—-Acacia dictyophleba.

A canoe in storage. Photograph courtesy of Karen Coote, Australian Museum

Problems encountered with wooden objects

Insect attack

Possible causes

• Softer woods are prone to insect infestation.

• Usually the infestation occurs before the tree is cut down, and insects emerge from the object because the conditions-relative humidity and temperature—are favourable for continuing their life cycle.

• Insect infestation shows itself by the typical frass and exit holes in the wood. The size and shape of the hole can tell an expert what insect has emerged.

Preventive action

Freeze the object:

• place the affected object in a plastic bag;

• remove as much air from the bag as you can. This reduces the amount of moisture which would otherwise be absorbed by the object or condense inside the bag;

• close the bag with a heat-sealer or waterproof tape;

• place the object, in its bag, in a freezer for 48 hours at -20⁰C; and

• then remove the object from the freezer and allow it to thaw.

Wood, leather, feathers, fibre and textiles can all be treated this way. This process kills insects at all stages of their life cycles.

Cracking

Possible causes

• Aboriginal wooden objects have often been cut and carved before the wood has had time to cure or season. This leads to preferential loss of water from particular areas of the wood as they dry out in the natural atmosphere.

Preventive action

• Place the object in a wetter environment, up to 60%RH. This slows down the drying rate and helps to reduce cracking.

Flaking paint

Possible causes

• Too little binding medium in the paint.

• Paint applied over unbound pigment.

• Environmental fluctuations causing movement of the wood, leading to flaking of the paint.

• Preferential shrinkage of some paints over others as the paint is drying.

Preventive action

• Wooden objects with flaking paint can be stored by supporting them on sand-bags, so that the painted areas are not under any pressure.