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Agents of Deterioration

Agent deterioration

An agent of deterioration is a term used to identify the nine major active agents that threaten museum collections. These active agents can be sudden and catastrophic or gradual over a period of time. Museums have employed and refined different strategies over the years to help mitigate these nine agents. However, these agents aren’t just confined to museums; take a look around your home or neighbourhood. How many of the agents can you identify?

The Agents:

Direct Physical Force (shock, vibration, abrasion, and gravity)
Physical forces can be sudden and catastrophic or gradual over a long period of time. Most artifacts are susceptible to this damage with the most common damage resulting from improper handling. The range of damage can vary from complete loss to minor fixes.

Results from: improper handing or support, earthquakes, war, floor collapse

Creates: Dents, scratches, breakage, and any sort of abrasion to all types of artifacts

Thieves and Vandals/ Disassociation
This type of damage can result in total loss of the object if care is not taken. There are a lot of preventative methods in place to help prevent this type of loss both for staff and visitors. Graffiti and overall intentional damage to objects or areas are also part of this category.

Results from:     Intentional- Theft, Graffiti

Unintentional- When staff lose or misplace an object

Creates: Disfiguring or loss of artifacts

Fire poses a threat to all collections both inside and outside of the museum. The smoke of a fire can often be just as dangerous and destructive as the fire itself. Although this is not a common occurrence, the loss and destruction is often severe.

Results from: fire and smoke deposits

Creates: Destruction. Can destroy, scorch, or deposit smoke on artifacts, especially organic materials

Water damage to metal post causing rust
Water damage causing rust on outdoor sign posts

A major threat to collections because water agents can begin from something as simple as a leaky roof to something catastrophic such as a flood. Organic materials, metals, and composite (layered) materials are the most susceptible to this damage.

Results from: Burst/leaking plumbing, floods, and rain

Creates: efflorescence/ tide marks on porous materials, swelling of organic materials, corrosion, delamination, fractures, and shrinkage or textiles

Mouse chewed artifact
Evidence of mouse chewing an artifact

Pests are common in both museum and home. In this category we can include both the pests themselves and their deposits such as nests and homes. Organic materials are the most susceptible because pests consider them wither a food source or a barrier they want to cross. The damage becomes greater when pests set up home in and around the objects.

Results from: Insects, Vermin, Birds, Mould and Microbes

Creates: cuts, tunnels, excretion, and gnaw marks. Can weaken, disfigure, and displace artifacts. Moulds can stain or weaken both organic and inorganic materials. Many times create irreversible damage.

Term used to describe the chemical agents from both controlled and uncontrolled environments that can accelerate the deterioration process.

Results from: Indoor and Outdoor gases (eg.Pollutants, oxygen), Liquids (eg.Grease) , and solids (eg. Dust and salt)

Creates: Disintegration, discolouration, and corrosion of especially reactive or porous materials.

Basket radiation
Basket affected by radiation on exterior, fading the original colours

Light damage can result from natural lighting such as the sun to the lightbulb lighting a room. Light damage will not cause complete destruction of an object, but it can decrease its relevance and decrease value considerably. This type of damage cannot be repaired or reversed.

Results from: Ultraviolet light, Unnecessary light

Creates: Disintegration, Fading, yellowing of organic and coloured inorganic materials, and darkening of woods.

Incorrect Temperature
All artifacts decompose gradually at room temperature but can take decades to visually see temperature impacts. Here are circumstances that can quicken the disintegration process;

Too High: gradual disintegration or discolouration of organic materials especially photos, films, and acidic paper

Too low: Embrittlement which can result in fractures of paints

Fluctuations: Fractures and delamination of layered material, and Relative humidity fluctuations

Incorrect Relative Humidity(RH)
Incorrect RH and temperature often go hand in hand since they impact each other. Think of all those summer days when it is sticky outside, that’s humidity. Objects are also impacted by humidity and the severity and types of damage can vary.

Damp: Causes mould and corrosion, hydrate materials

Fluctuations: Shrink/ swell unconstrained organic materials, crush or fracture constrained organic materials, and cause layered organic materials to buckle, tent, or delaminate

Dry: Fracture materials


Susan M.

The first picture makes me think of agent orange and it was my belief that there were 10 main agents of deterioration… Sorry, had to say something..

– Susan


Hi Susan,

Thanks for your comment. You are correct as some lists do vary between 9 and 10 agents of deterioration. Typically this is because some lists make Disassociation/Displacers (the internal loss/misplacement of an object) its own category. Our list is based on Leicester Readers in Museum Studies “Preventative Conservation in Museums” 2011 where Disassociation is grouped with Thieves and Vandals.

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