The effects of incorrect or fluctuating relative humidity (RH) on an object can be disastrous. However the level and nature of damage sustained depends on a variety of factors including the materials it is made from, its previous, current or intended use, and the method of construction. In many cases, it is the RH fluctuations, particularly those which occur over a short period of time, that cause the most problems. However, RH that is continuously too high or too low can also be highly problematic.
Objects comprised of organic material such as wood, textiles, leather, vellum and paper-based items, are more likely to be affected by fluctuating RH than inorganic materials such as glass and stone. The effect of incorrect or fluctuating RH on organic or sensitive materials can include mould growth, increased biological activity (insects and pests) and dryness or brittleness, which can be especially harmful for paper and leather objects. Inorganic materials, such as metal and ceramics, can also suffer long term effects of incorrect or fluctuating RH. These effects include the corrosion of metals, and the crystallisation of salt on the surface of some stone or ceramic material.
Environmental monitoring programs
Incorrect or fluctuating temperature does not usually directly affect an object or collection, however it can affect the RH of an environment. It is therefore equally as important to monitor the temperature in your object's environment as it is to monitor the RH.
We can assist you in understanding the environment in which your object or collection is housed by implementing an environmental monitoring program. An environmental monitoring program is designed to monitor the RH and temperature of an area or areas over a certain period of time in order to gain an understanding of the patterns and fluctuations. It enables us to build a picture of the environmental situation in conjunction with an assessment of the objects, and provide recommendations to address any issues.
If you would like more information regarding an environmental monitoring program for your collection, please contact us.
Guidelines for environmental conditions
Guidelines for environmental conditions in Australian museums and galleries, to be published by the Australian Institute for the Conservation of Cultural Material (AICCM) are currently in development, and are due for public release in 2012.