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Late in 2022, Somerset Archives were informed that a series of 20th century business records had been found by developers in a disused premises in South Somerset. The archives, which had been stored for over twenty years in a sealed window-less room, were suffering from damp and severely affected with active mould.
A sample of the records were selected for permanent retention, then wrapped and packaged on site for transportation to the Somerset Heritage Centre. Once returned to the Heritage Centre the documents were laid out to dry, with daily monitoring. The following spring the mould was cleaned from the volumes, when this could be done outside.
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Challenges and opportunities
Please describe any challenges or opportunities you faced and how you responded to them
The Somerset Heritage Centre does not have a drying room, or separate fumigation suite, so alternative accommodation was needed to dry the mould without contaminating other archival material. Staff re-purposed their Sort Room, covered shelving and other equipment with plastic sheeting and laid the volumes out to dry. A dehumidifier was also used.
The volumes were checked every day to ensure they were drying sufficiently, and where necessary pages of books were turned to ensure even drying. Apart from the staff doing the daily checks, who always wore suitable Personal Protective Equipment (PPE), the room was out of bounds to all other staff.
After the documents were dry and the was mould inactive, staff wrapped them in acid-free tissue, and stored them in a temporary location in the strongrooms. Relative humidity (RH) levels below 55% made certain the mould would not reactivate. The Sort Room was then cleaned with alcohol to ensure that mould spores did not transfer to other collections, and to ensure that the room was safe for staff use.
Without access to a specific drying room or fumigation suite, the decision was made to clean the documents outside. Staff waited for a dry sunny day to set up a cleaning station in the staff car park. With staff wearing appropriate PPE, they brushed the surface of the documents, ensuring that the mould and dust was brushed away down-wind from the staff.
The documents were then packaged in archive boxes and moved to permanent storage in the strongrooms, where the environmentally controlled conditions will ensure no re-growth of the mould.
Outcomes and lessons learnt
What were the outcomes for service users?
Without treatment the documents would have been unsafe to use, with the mould causing a danger to health. In addition, a catalogue could not be compiled, and needs for further conservation work could not be considered. The storage of damp documents with active mould within strongrooms would have put other collections at risk, and would have caused further degradation and loss of information from the documents. By drying and cleaning the documents it has made them accessible for research, and for a catalogue to be completed in due course.
Describe what you learned from the process: what went well? What didn’t go quite as well?
The dehumidifiers located at Somerset Heritage Centre, Devon Heritage Centre and within Somerset Museum Service were old and did not have high efficiency particulate air (HEPA) filters, so a suitable dehumidifier and spare filters were ordered. This dehumidifier can now be used across services in the future wherever the need arises. The team used one of the older machines while waiting for the new dehumidifier to arrive, enabling them to start the drying process.
Before doing so, they covered the furniture in the Sort Room with plastic to minimise the spread of the mould spores and to limit the need to remove items from the space. Additionally, as archival packaging is stored in the Sort Room, the team did not want this material to become contaminated. This plastic has been retained for any future treatment of mould infestations.
Staff were forced to store the dry but untreated documents in the strongrooms for an extended period of time, while waiting for suitable weather and staff availability to clean them. This was not ideal, best practice being to keep mouldy collections away from the strongrooms. To minimise the risk of cross contamination, staff ensured that the documents were well wrapped in archival tissue, were placed on empty shelving in an isolated part of the strongrooms, and surrounded with pest traps.
This project is an example of how large mould infestations can be managed without the relevant dedicated facilities, such as a drying room, fume cupboard or isolation suite.
If someone was thinking about taking on a similar project, what would be the one piece of advice you would give them?
Ensure that the proper material and equipment is available on site as part of routine supplies. The team were given short notice for the collection of these documents, as the developers were keen to progress with their plans. This meant that there was little time prior to collection to ensure the correct equipment was ordered and available. Staff had to make decisions at speed, such as finding an appropriate space to utilise for drying.
Having a dehumidifier with a HEPA filter on the premises would have made the drying process quicker and easier and would have decreased the need for the cleaning of the Sort Room once the documents were dry.
Thinking through the use of spaces which can be utilised for the isolation and drying of mould infested collections within premises would also be beneficial. While the Sort Room was not ideal, it did provide a useful space, however it meant that staff had to delay the deposit of larger collections, which would normally be stored in the Sort Room while being processed.
How will this work be developed in the future?
This experience has not only provided staff with the relevant equipment, but also the staff know-how to deal with similar issues in the future. Archivists worked together with the Senior Conservator, so the knowledge base has been shared, meaning if the situation arose again – for example, the Senior Conservator was on holiday – treatment could be started immediately following the procedures developed through this experience.
The team will also ensure that more staff are trained in basic conservation practices, such as cleaning and packaging, as an extension to our Disaster Preparedness training. This will ensure that skills continue to be developed among all staff and so there are always staff available at short notice or in an emergency situation.