MOULD

MITIGATION AND PREVENTION

Presentation by Simon Dimech

Reporting on BREAKING THE MOULD course,

Preventive Conservation Department of The Bodleian Libraries,

University of Oxford

Sponsored by the Friends of the National Archives

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Presentation by Simon Dimech

•What is Mould?

•Deterioration of Archival Collections

•Health and Safety

•Detection and Assessment

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•Mould @ NAM

•Response Procedures

• Possible Treatment Steps

•Cleaning of Inactive Mould

•Preventive Measures

What is Mould?

• Mould is a microscopic fungi (4-60 microns) and

hence mostly cannot be seen

• Mould is ubiquitous and it is a natural decomposer

and hence cannot be eliminated

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and hence cannot be eliminated

• Mould needs to feed on other materials in order to

gain energy

• Mould thrives in environmental conditions of pH 3-8,

Temperature 10-35oC and require moisture (water

activity)

• The growth can become visible in 48 hours

• Due to their ability to form hypha mould networks penetrate

materials deeply, resulting in material loss due to acid

corrosion, enzymatic degradation and mechanical attack

• It was noted that when fungi destroy paper, water is liberated

Deterioration of Archival Collections

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• It was noted that when fungi destroy paper, water is liberated

and hence a colony of fungi can accumulate enough water so

that growth is independent of the ambient RH

• Natural materials are more reactive to mould than synthetic

materials

• Organic compound found in archival collections serve as a

carbon source for fungi

Health and Safety

• Staff awareness

• Risk increases with frequency and duration of exposure

• Sensitivity through inhalation and skin contact

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• Sensitivity through inhalation and skin contact

• Symptoms include headaches, nausea, flue-like

symptoms, irritation of skin, eyes, throat and lungs,

including alveolitis and pulmonary hemosiderosis

• Annual health surveillance to personnel being regularly

exposed to mould

• Quarantine areas for use when mould is found

•Vacuum cleaner having variable power and HEPA filter

Safety equipment and protective clothing

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•Face Masks (FFP3)

•Disposable Gloves

•Disposible aprons/ lab coat

•Protective eye ware

• The difference between active and inactive mould, and how

to recognize it

� Active mould: Damp and fluffy, If touched it will smear

and stain

Detection and Assessment

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and stain

� Inactive mould: Dry &powdery, if touched it does not

smear or stain

� Both active and inactive mould are equally dangerous

once inhaled, but active mould is easier to inhale

� Inactive mould can become active once the right ambient

conditions are present

Different cases

of active mould

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Different cases of

inactive mould

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Mould @ NAM

• From the conditon assesment survey it results that 17.4%

of the collection is affected by inactive mould

Any presence of mould identified by the reading room

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• Any presence of mould identified by the reading room

staff is reported through a Damage Report Form

• Priority in treating active mould is given whenever this is

identified

• Treatments are carried out at the Conservation Laboratory

Response Procedures

The first step is to assess the severity of an outbreak and in order

to do this the following questions have to be answered:

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� How much material is affected?

�Is only one type of material affected?

�Is only one area affected?

�How extensive is the mould growth?

�Is it dormant or active?

Subsequently the following considerations have to be taken:

�The possibility of culling and replacing badly affected items

�The possibility to isolate affected collection or area

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�The possibility to isolate affected collection or area

�Checking of HVAC or similar systems

�To determine if the problem can be dealt with in-house.

Possible Treatment Steps

• When affected items have to be moved, they must be sealed in a

polyethylene bag to prevent the spread of spores

• If treatment cannot be carried out immediately mouldy items

should be dried and freezed

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should be dried and freezed

• To dry active mould warm air should not be used, instead fans,

dehumidifiers and cool air should be used

• The use of a fume cupboard is recommended for safe drying and

minimal exposure

• Mouldy material can be air dried if holdings are non special-

collection and more robust

Cleaning of Inactive Mould

• Special care must be taken when cleaning archival material from

mould since the material tends to be weakened by the mould itself,

and further damage can take place

• Always consult a Conservator before intervening on archival material

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• Always consult a Conservator before intervening on archival material

• The Conservator will check the stability of the artefact and which

treatments can be safely carried out

• Cleaning can be done using a soft brush and a variable power

vacuum cleaner with Hepa filter

• The most common disinfectant used is 70% ethanol in water. Ethanol

can also have a good fungitoxic effect if the contact time is at least 2-

3 min.

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Cleaning of mould using a low power vacuum cleaner fitted with a soft brush and Hepa filter

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Two cases of bad storage leading to

mould growth found by our Records

Officer .

Preventive Measures

• In order to avoid future outbreaks an affected area has to be

thoroughly cleaned and sporadic spot-checks must be done

• Building issues which may have caused the mould outbreak

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• Building issues which may have caused the mould outbreak

have to be dealt with

• It must be ensured that the environment is kept cool dry and

stable (ideally Temperature should be 18-22°C & RH 60-65%)

• Steps to stop spores from entering the building have to be

taken

• Storing items against external walls is to be avoided

• Room for air circulation has to be left

• Items are to be cleaned and inspected regularly

• Wet books with no sign of mould these have to be

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• Wet books with no sign of mould these have to be

dried in order to prevent any future mould infestation.

• Equipment such as brushes and containers used with

mouldy items must be cleaned after being used, in order

not to contaminate other objects.

The Conservation Laboratory at National Archive

of Malta would be pleased to help and

advice other institutions in the mitigation and

prevention of mould

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prevention of mould

Thank you