Biological Pests

What can be done to control moulds?

It is impossible to stop fungal spores falling on objects. Because of this we must concentrate our efforts on making the environment unfavourable for their development into a mould colony. This can be done by controlling the relative humidity—RH.

If the relative humidity is maintained at a low enough level—that is, below 65%—spores cannot germinate. It is safer to aim quite a bit lower than 65%, because if the relative humidity hovers around this level, fluctuations in temperature could cause the relative humidity to rise above 65%. Certainly between 45% and 55% is considered safe. If the relative humidity is too low—that is, below 45%—some materials can be damaged.

In many situations—such as in buildings without air-conditioning—it can be difficult to control temperature and relative humidity. But there are other steps which can be taken.

Consider the location of materials which are susceptible to mould infestation. If they are against damp walls or in contact with cold surfaces, the local relative humidity may be high enough to permit mould growth. Move any items which are likely to be affected in this way, or wrap them and box them to protect them.

Make sure there is adequate ventilation in storage and display areas. Breezeways are vital in tropical areas.

Try to make sure all materials which could support mould growth are stored in acid-free wrappers or boxes, or are at least covered with dust covers.

Keep objects which are on open display clean.

Make sure the microclimates in display cases are suitable and will not create a favourable environment for mould to grow.

Inspect collections regularly. Don't let the mould grow for months before you find it.

Make sure the building is well maintained. Check for problems such as broken pipes, blocked gutters, rising damp from damaged water mains, broken sewer pipes, inadequate damp coursing and leaky roofs.