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10 Agents of Deterioration

By Pam Murray, Wellcome Project Conservator

17 April 2020

Many people think that an archive is there just to keep books, maps, files and photographs safely in a dark room. But in actual fact the archivists, collection managers and conservators of an archive work hard to ensure the collection is protected from things that can cause damage. The main forces that can cause damage to a collection are often referred to as the 10 agents of deterioration. All of these forces can have a negative impact on a collection, and we try to ensure that we minimise the deterioration as much as possible.

Different materials might have a higher risk of damage from a particular agent of deterioration. For example, certain insects might be a higher risk to a textile collection than to an archaeological metal collection. Minimising these impacts whilst balancing access is at the heart of our collections care policy. So, let’s have a look at the 10 agents of deterioration that we try to safeguard the Bath Record Office collection from.

Physical Forces

Physical forces can damage items in two ways: An immediate impact and a slow impact of physical force. An immediate impact could be an item falling off a shelf from poor packaging or being too heavy to carry, so the item gets dropped. A slow impact of physical forces occurs through improper handling during research or educational purposes. This could be a lack of sufficient support for a spine of a book or touching an item with dirty hands. Physical forces are generally caused by poor handling or by accident. We try to minimise the damage of physical forces by washing our hands regularly, using supports for items and packaging collections in manageable boxes and folders.

A map with many tight folds makes it difficult to handle and open

Thieves, Vandals, Displacers

This can come in the form of a planned theft, an opportunist theft, staff embezzlement or vandalism. We can’t share too much about our security plan for obvious reasons, but security cameras, locks and access codes, alarm systems, security checks, retrieval slips, and guards can all play a role in preventing theft, vandalism and displacement.

A police mugshot from Register of Prisoners, Bath City Police [ref 0661/4/1/1]


Fire can be devasting and can cause damage from smoke or burning, or a complete loss of a collection. Prevention from fire happens on many levels, including smoke detectors, fire extinguishers, fire doors, and eliminating fire hazards in the strong rooms. Good housekeeping is the best way that we can prevent a fire; we regularly test our fire equipment to ensure it is in working order, we always close doors after any retrieval, and complete a fire safety assessment with Guildhall staff.

A historic Bath City Council sign when smoking was common practice in the workplace


Leaks or ingress from pipes or rain can cause severe damage to our collection. Because our collection is housed in the basement of the Guildhall we are at risk from leaks. Water damage could occur from anything from spilling a glass of water to a leaking pipe or a flood. Installing flood detectors, sealing windows, carrying out routine checks, and ensuring our collection is off the floor can help us mitigate the damage before it gets worse. Having all the equipment we need to deal with a leak is also helpful in preventing severe damage. Water can cause tidelines, inks to run, and tearing if an item is handled poorly when wet.

Water rate registers, Bath Record Office


Pollutants can come in many different forms. Originating from within the building or outside the building. They can be in a gaseous form or a particulate form. Sometimes even the collection itself is the cause of the pollutants. For example, boards that are used to mount artwork can be acidic and this can then directly transfer to the artwork creating a matt burn. Particulate damage can come from dust, which is often made up of clothing, skin, hair and also building materials. Gaseous pollutants can come from adhesives, textiles, wood, and burning fossil fuels. Using tested materials and buffering from sources outside our control are important steps to prevent pollutant damage.

Engine 568 at the platform at Green Park Station Bath c.1947 [courtesy of Bath In Time]


Pests can cause great damage and even complete loss to a collection. Pests include both rodents and insects. Our Pest Management System includes good housekeeping, a no food or drink policy, and frequent monitoring. Insects are very sensitive to temperature and humidity, so monitoring our environmental levels also gives us more information. There are so many different pests out there and knowing what pests to look for means we can target the specific pests that threaten our collection. Mould is also sometimes categorised as a pest too, due to the fact that it grows. Keeping humidity levels below 60% is the number one way to prevent mould growth.

Damage from pest larvae eating through pages of a wages book


Light in the form of ultraviolet, infrared or visible light can cause cumulative damage. Light damage is irreversible and some items like photographs and watercolours are very sensitive to light. Bath Record Office has most of the collection stored out of light for this reason. When items are sent on loan, a risk assessment can be carried out to decide how much light an item can be exposed to and for how long.

Colonnade in Bilbury Lane, 1958 [courtesy of Bath In Time]


Fluctuations in temperature or items that are sensitive like photographs can deteriorate faster in higher temperatures. The effects of temperature being too high or too low can sometimes only be apparent over a long time, so can easily be overlooked. Temperature is a big issue at the moment in cultural institutions, because we are balancing the comfort of people and the energy required to keep a certain temperature, and more and more we are looking at how climate change is affecting temperature for buildings, loans and research.

Taking weather readings on top of the Guildhall, Bath [ref: Acc 42 45]

Relative Humidity

If the relative humidity increases then organic materials (like leather or paper) absorb the moisture and if the humidity drops then the materials give off humidity and can shrink. If this happens often or suddenly then cracking, warping or cockling can occur. In inorganic materials like metal, high humidity levels could trigger corrosion.

Corroded paper clip stain and distorting paper item


Disassociation or custodial neglect is a large aspect of our work. The first is when the previous mentioned agents of deterioration are not actively mitigated or out of date practices are used. The second is a disassociation with records. If records and the items are disassociated, then the item loses meaning and value. This is one of our highest priorities. This can occur through poor labelling, losing track of an item. An example would be if a number that links an item to a report is removed from the item, then all the records in relation to the item are lost too, losing its history.

This list helps the Record Office staff create a collection care policy and assess the risks to our collection, making sure researchers can access more collections safely, for longer. These 10 agents of deterioration can also be used for your personal collection at home, to help preserve them for longer.

Clerk's original wrapper around receipts from the Bath Improvement Commissioners, Bath Record Office