Arid

This climate is generally very dry, however, in arid areas, it is often very hot during the day and very cold at night. This wide fluctuation in temperature is matched by wide fluctuations in relative humidity, for example from 75%–20% in a day.

When caring for Aboriginal and Torres Strait Islander heritage items in arid climates it is important to note:

• many of the materials that make up these items will tend to give out the water they contain–this can lead to some items, and some components of items, becoming dry and brittle; and

• the composite nature of many Aboriginal and Torres Strait Islander heritage items means that they are particularly susceptible to damage from fluctuations in temperature and relative humidity. As different materials release moisture at different rates, warping, dimensional change and flaking of paints can result.

Remember that even arid areas can have periods of higher relative humidity, even though the periods may only be very short. High humidities will cause swelling of some materials, and will increase the likelihood of insect and mould attack.

Dust can be a major problem in an arid climate. It is important that steps are taken to protect items from dust in storage and display.

Note: If your collections of Aboriginal and Torres Strait Islander heritage items have been kept in an arid environment for a considerable period and they are stable—do not try to alter the environment to meet the recommended ideal conditions. This could do more harm than good. The emphasis should be on long term stability.

Temperate

A temperate climate is considered a moderate climate, however, temperate climates tend to have a greater range of temperatures than tropical climates and may include extreme climatic variations.

If you are redecorating or designing storage and display areas, consider using materials that will help to buffer these areas against rapid fluctuations and extremes of relative humidity and temperature. This will help to reduce the risk of damage due to the fluctuations and extremes that occur in temperate environments.

The system of layers of storage—boxes, boxes within cupboards and drawers, covering items on shelves, etc—will be very useful in helping to buffer against the extreme conditions that can occur in a temperate environment.

As for all climatic areas regular inspection of storage and display areas is important so that developing problems do not go unnoticed.

Remember that many of Australia’s main cities and major regional centres are in temperate regions. These areas tend to be heavily polluted and this should be taken into account.

Note: If your collections of Aboriginal and Torres Strait Islander heritage items have been kept in a temperate environment for a considerable period and they are stable—do not try to alter the environment to meet the recommended ideal conditions. This could do more harm than good. The emphasis should be on long term stability.

Tropical

These climates are characterised by heavy rainfall, high humidity and high temperatures.

When caring for Aboriginal and Torres Strait Islander heritage items in tropical climates it is important to note that:

• insects and moulds thrive and reproduce readily;

• chemical deterioration reactions generally proceed faster at higher temperatures;

• materials that have been in a tropical environment for some time will have a high moisture content. If they are suddenly moved into a drier environment they are likely to suffer shrinkage and warping;

• many of the materials used in making Aboriginal and Torres Strait Islander heritage items are very reactive to changes in relative humidity; and

• composite works will be particularly vulnerable.

Take steps to ensure that your storage and display spaces have good air flow.

Note: If your collections of Aboriginal and Torres Strait Islander heritage items have been kept in a tropical environment for a considerable period and they are stable—do not try to alter the environment to meet the recommended ideal condition. This could do more harm than good. The emphasis should be on long term stability.