Dealing with mould

What is mould?

The air is full of fungal spores of all kinds. These spores can be carried by air currents and deposited on surfaces such as books. If the conditions are right the spores germinate and grow into fungus.

Mould is just one type of fungus. Mould can be detected by the presence of powdery material, multi-coloured pigmentation, staining or a musty odour. Mould can be extremely destructive to library materials, causing weakening of paper, vellum and leather and loss of text or image.

Health issues

Mould can pose a serious health risk, so safe handling of infested material is essential. Certain types of mould cause lung, skin and eye irritation and each person can have different sensitivities. People who suffer from allergies, asthma or respiratory problems should not attend to mould infestation. Safety precautions for handling include:

  • wearing disposable gloves, a high-efficiency particulate air (HEPA) filter respirator, and protective clothing such as an apron or lab coat
  • washing hands, face and clothing after handling
  • disposing of contaminated gear and equipment (where appropriate) after handling
  • avoiding extensive handling - the longer you are exposed to mould the greater the chance of developing sensitivity
  • being aware that fungicides and biocides can be a health hazard and must be used in accordance with very strict rules and regulations
  • seeking professional help if the outbreak is discovered in a large portion of the collection. Refer to the AICCM Conservators in Private Practice or look under Pest Control in the Yellow Pages.


What to do with an outbreak of mould

Step 1  Make an initial assessment to see how many items are affected and whether a conservator or pest control company should be consulted. You may want to contact a conservator if the material is valuable or fragile. Conservators will have the skills to strengthen or repair an item and possibly reduce staining.
Step 2  Isolate the affected material by placing in a plastic bag and moving to a separate area that is clean, cool and dry with lots of fresh air. Bagging and moving the material will prevent the mould spreading to nearby items.
Step 3

Mould is usually caused by excess moisture so the next step is to dry your material out. This will stop the mould growing. Line your work surface with paper that can be thrown out afterwards. Take the material out of the plastic bag and place on the paper. Use a fan to assist the drying process but ensure that you have windows and doors open so the spores are released outside. Dehumidifiers can assist in removing excess moisture in the air. You can also place the material outside in the sun, but do not leave for longer than 10 minutes as heat and light can cause fading and degradation.


Step 4 Once your material is dry; remove the mould by brushing it off the surface. Unused shaving brushes are useful for this purpose. Brush away from yourself into a vacuum fitted with a HEPA filter, or towards an open window. After cleaning, seal up vacuum bags and disposable equipment in a bag and dispose outside in the garbage bin.
Step 5  Clean the infected storage areas before packing or re-shelving. Wet wipe surface areas using household bleach prepared according to the label. Ensure area is completely dry before replacing material.
Step 6 Make sure the conditions that supported the mould growth have changed. See the following section below.

How to help prevent mould returning

  • Keep storage areas clean and free of dirt, dust and organic debris – these provide nutrients for mould growth. The items themselves may be cleaned gently with a soft brush (fragile items should be treated by a conservator).
  • Mould needs moisture and warm temperatures to survive. Your storage environment should be cool, dry and stable, with good air circulation.
  • Regularly inspect the area for evidence of mould activity. This will allow you to catch any infestation before it becomes large.
  • Do not pack or shelve books too tightly, allow air to circulate.
  • Do not shelve books directly against an outside wall. Due to temperature and humidity differences between inside and outside environments, moisture may develop along walls and cause mould growth.
  • Make regular inspections of storage areas and material for signs of mould.

Further reading

Florian, Mary-Lou. 1997. Heritage Eaters: Insects and Fungi in Heritage Collections. James and James, London.

Zycherman, Lynda A. (ed). 1988. A Guide to Museum Pest Control, Foundation of the American Institute for Conservation of Historic and Artistic Works and the Association of Systematics Collections, Washington.

The British Library - National Preservation Office Leaflets. Prevention and Treatment of Mould Outbreaks in Collections.

Please note

We are unable to give advice on conservation treatment of items.

The advice we are able to give is limited to what we understand to be ethical and safe for people and items.

For treatment purposes we recommend that you contact a professional conservator, who will be able to assess each individual item and give it appropriate treatment. A conservator will charge a fee.

Further information

Australian Institute for the Conservation of Cultural Materials

or contact

Collection Preservation & Storage Branch
State Library of New South Wales