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.

Steps that can be taken include:

• storing metals in cabinets, boxes and wrappers to buffer the objects against short-term upward swings in relative humidity. Protection against dust is also achieved in this way.

• using insulation and sensible house-keeping practices which minimise the differences between internal day and evening temperatures. The corresponding fluctuations in relative humidity should be minimised.

Note: If your collections of metal objects have been stored 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.

Steps must still be taken to overcome the extreme climatic variations which occur in these areas.

High relative humidity conditions can be counteracted by:

• displaying metal objects in sealed cabinets to overcome short term variations in relative humidity and temperature;

• store metal objects in cupboards, boxes and wrappers to buffer against variations in external conditions; and

• protect metals by coating them with water repellents such as CRC, WD-40 or waxes. Consult a conservator before doing this.

Note: If your collections of metal objects have been stored 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.

To counteract the problems associated with high relative humidity and generally high temperatures that characterise these regions the following strategies can be adopted:

• place sensitive metals in well-sealed cabinets and maintain the relative humidity at a level below 45%;

• use cabinets, boxes and layers of acid free tissue to create buffer zones which will reduce the impact of high relative humidity and temperature on metals;

• use portable dehumidification units during periods of high relative humidity; and

• inspect metal objects regularly and maintain high standards of cleanliness.

Note: If your collections of metal objects have been stored in a tropical 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 that good. The emphasis should be on long term stability.

Coastal Regions

Coastal regions generally have more moderate climates than inland areas but they also have high levels of wind-borne salt. Consideration must be given to counteracting the corrosive effects of salty air.

Steps which can be taken include:

• storing and displaying metals in sealed cabinets to buffer against environmental changes and to exclude dust and salty air; and

• putting multi-metal vapour phase inhibitors, such as Senson, in sealed storage and display areas.

• sealing buildings to minimise air exchange with the external, salt-rich air, by keeping doors and windows closed, eliminating drafts and using airlock doors.

• maintain relative humidity below 45% in storage and display areas.

• treat metals with moisture agents—waxes are recommend—and corrosion inhibitors.