Temperature and Humidity

Humidity is the amount if moisture found in the air. High temperature and humidity levels work together to speed up the process of chemical and biological deterioration. 

Corrosion is a common form of chemical deterioration affecting metals coming into contact with oxygen and moisture, making them brittle. 

 

Metal objects containing iron will form a layer of reddish iron oxide or ‘rust’ during corrosion.  This layer of rust continues to react with oxygen and moisture in the environment, becoming flaky, powdery or sometimes forming a solid crust.  With time, the rust may flake off. 

The door knob on the left was treated while the one on the right was left untreated.

 

Copper reacts with moisture, especially acid rain, to form copper carbonate, also known as ‘patina’.  This insoluble layer of greenish substance protects the copper object from further corrosion.  The bronze door knob is a good example of this phenomenon. 

Non-metals also react to moisture in the air.  Organic materials such as leather, wood, fibres in textile and wood pulp in paper absorb and release moisture in the air, resulting in expansions and contractions which can cause physical damage to the object over time. 

The humidity level of a typical sunny day in Singapore is about 80% to 90%. Museums work to maintain temperatures at about 23°C and humidity levels within 50%-60% in their galleries, as this is the best environment for the preservation of most objects. 

Mould is a type of fungus that can be found on all materials, although organic materials such as wood and leather are more prone to mould growth. 

 

Mould spores are extremely small (0.001mm to 2mm).  It can stain and change the physical appearance of the object.  Some moulds even take on the colour of the materials they consume. Mould is a type of fugus that can be found on all matrials, although organic materials such as wood and leather are more prone to mould growth. 

Mould spores are extermely small (0.001mm to 2mm). It can stain and change the physical appearance of the objecct. Some moulds even take on the colour of the materials they consume. 

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