Agents of Deterioration

Robert Waller of the Canadian Museum of Nature and Stefan Michalski of the Canadian Conservation Institute have been the primary proponents of applying risk management strategies to museum collections. This approach has found wide acceptance in the preservation community as a tool for helping institutions assess risks to collections and find an appropriate balance between the requirements for use (i.e. research, display and education) and preservation. 

Examining whether a risk is likely or unlikely to occur and whether it would result in minor or major loss aids in setting preservation priorities.  Risk is broken down according to ten agents of deterioration  that pose threats to collections. 

Light, Ultraviolet, and Infrared

Damage from exposure to visible light, and ultraviolet and infrared radiation is cumulative and irreversible. It is a function of intensity over time, and therefore even low intensity light can make an impact if objects are exposed over a long period time. Common impacts are fading or discoloration, as well as unseen chemical changes that cause embrittlement in organic materials.

Examples of Damage

A taxidermy mount of a skunk standing on a wooden base with head down and tail curved down towards the body.

Example of deterioration from light: the fur on the top of the skunk is brown, which is not the natural coloration of the species but discoloration from light exposure.
F. Ritchie/© AMNH

Two images of a black and white ruffed lemur taxidermy mount. The lemur is positioned sitting on a branch and the mount is on a tabletop.

Example of deterioration from light: this black and white ruffed lemur taxidermy mount discolored before conservation treatment on the left, and after re-coloring treatment on right. Note in the before treatment image that the dark areas of fur are brown when light damaged, and the white areas are yellowed.
F. Ritchie/© AMNH

Two mammal taxidermy mounts in an open storage drawer with several flat study skins. The mounts are lighter in color than the skins.

Example of deterioration from light: the two taxidermy mounts in this drawer are lighter in color overall than the study skins on the right side of the drawer. The taxidermy was exposed to light and faded over time, while the skins were protected in storage and retain their original darker color.
F. Ritchie/© AMNH

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Preventive Care Strategies for managing Light, Ultraviolet, and Infrared
CCI Agents of Deterioration: Light, Ultraviolet, and Infrared

Incorrect Temperature

Temperature is a measure of heat energy, and damage may occur when the temperature is either too high or too low. High temperatures increase the rate of chemical reactions, soften materials, and desiccate organic materials. Low temperatures can cause hazing and cracking. Temperature directly affects relative humidity, and consequently a fluctuating temperature leads to a fluctuating relative humidity.

Examples of Damage

A close-up image of the underside of the nose of a taxidermy mammal mount. The nose is constructed out of wax and there is one flat end that does not match the curve of the rest of the nose.

Example of deterioration from exposure to incorrect temperature and physical forces: the wax nose of this mammal taxidermy mount is flattened on one side because of incorrect temperature (too high) combined with physical forces (incorrectly stored resting on the end of the nose).
F. Ritchie/© AMNH

A close-up image of pointy shark teeth, several with splits running the length of them.

Example of deterioration from exposure to incorrect temperature: the teeth of this shark jaw are cracked and there are areas of loss. The condition occurs when teeth are exposed to low RH and low temperature. Real skulls and teeth are often used in taxidermy mounts.
J. Sybalsky/© AMNH

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Preventive Care Strategies for managing Temperature
CCI Agents of Deterioration : Incorrect Temperature

Incorrect Relative Humidity

Relative humidity (RH) is a ratio (expressed in percent) between the mass of water vapor in a fixed volume of air (the absolute humidity) and the maximum mass of water vapor that a fixed volume of air could hold (without condensation) at the current temperature. All organic materials and some inorganic materials absorb and release water depending on the relative humidity of surrounding air. High RH can cause mold growth and corrosion; low RH can cause shrinking and cracking in organic materials.

Examples of Damage

The open mouth of a black bear taxidermy head on a skin rug. The pink tongue is visible, and the surrounding teeth are broken and have missing pieces.

Example of deterioration from prolonged exposure to incorrect RH: the teeth of this black bear skin rug with original skull are cracked and there are areas of loss. The condition occurs when teeth are exposed to low RH and low temperature. Real skulls and teeth are often used in taxidermy mounts.
F. Ritchie/© AMNH

Close-up image of the head of a polar bear taxidermy mount. There are several dark lines in the white fur around the nose that are splits in the skin.

Caption: Example of deterioration from prolonged exposure to incorrect RH: several splits in the preserved skin of a polar bear taxidermy mount. The largest split is wide and lifting from the mannikin.
F. Ritchie/© AMNH

The face of an opossum taxidermy mount. The nose skin is out of place because it is lifting away from the underlying mannikin.

Example of deterioration from prolonged exposure to incorrect RH: the skin around the nose and mouth of this North American opossum taxidermy mount is splitting and lifting away from the mannikin.
F. Ritchie/© AMNH

Close-up image of a seal pup taxidermy mount. There are several dark lines in the light-colored fur around the face that are splits in the skin.

Example of deterioration from prolonged exposure to incorrect RH: several splits in the preserved skin of a seal pup taxidermy mount.
F. Ritchie/© AMNH

Close-up image of a seal flipper that has three large splits in the skin. There are pieces of the internal mannikin coming out of the splits in the skin.

Example of deterioration from prolonged exposure to incorrect RH: three large splits in the flipper skin of a seal taxidermy mount. The splits have opened wider over time, due to fluctuations in RH, and the mannikin material is now coming out of the mount.
F. Ritchie/© AMNH

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Preventive Care Strategies for managing Relative Humidity
CCI Agents of Deterioratio n: Incorrect Relative Humidity

Pollutants

Pollutants are derived from contaminants produced both outside and inside of collecting institutions. Particulate and gaseous contaminants can be airborne, transferred by contact, or contained (inherent) within objects themselves. Common examples of pollution include dirt, soot, volatile components from plastics and wood, and residual pesticides.

Examples of Damage

View of the back of a bird taxidermy mount in a diorama, surrounded by leaves. It has a hazy appearance except for where a stripe of dust was removed.

Example of deterioration from pollutants: this bird taxidermy mount on display in a diorama has a thin layer of dust accumulation that is creating an overall hazy appearance. There is a dark stripe in the middle of the back where the dust was removed that reveals the actual color of the feathers.
J. Sybalsky/© AMNH

Side view of a mallard taxidermy mount standing on a table. The feathers along the head and side of the body are clumped together in an unnatural way.

Example of deterioration from pollutants: the feathers on the head and body of this mallard taxidermy mount are dislodged because of an accumulation of oil emitted from the skin. If fats and soft tissues are not fully removed during the taxidermy mounting process, oils will deposit onto the feathers and cause clumping.
F. Ritchie/© AMNH

Close-up view of the nose of a deer taxidermy mount with a white line running through half of the photograph.

Example of deterioration from pollutants: the nose of a deer taxidermy shoulder mount before removing a thick layer of dust accumulation (left side of photograph) and after removal (right side of photograph).
F. Ritchie/© AMNH

Taxidermy shoulder mount of a big horn sheep on a dusty floor. The white hairs of the sheep have an dark and hazy appearance from dust and soot.

Example of deterioration from pollutants: this big horn sheep taxidermy shoulder mount has an overall hazy and dark appearance from dust accumulation. The dust most likely includes soot from coal-burning heating systems, turning the white hairs a dark color.
F. Ritchie/© AMNH

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Preventive Care Strategies for managing Pollutants
CCI Agents of Deterioration : Pollutants

Pests

Museum pests are animals and microorganisms that are attracted to and capable of consuming or otherwise damaging museum collections and/or their storage and exhibit materials. Most prominent are invertebrate pests, such as moths and carpet beetles, but vertebrates such as rodents, and microorganisms like mold, can also cause catastrophic damage.

Examples of Damage

Taxidermy mount of a dwarf antelope standing in front of a grey background. The legs have large areas of hair loss that are visible as patches of white among the brown hair.

Example of deterioration from pests: there are large white areas on the hind legs of this dwarf antelope taxidermy mount that are areas of hair loss from moth infestation.
F. Ritchie/© AMNH

A close-up image of the hair of a dwarf antelope taxidermy mount. Across the surface there are many loose hairs and tufts of hair, as well as an area that has hair loss. There are also light-colored dots scattered over the brown hair that are moth frass (excrement).

Example of deterioration from pest: loose hairs sitting on the surface of a dwarf antelope taxidermy mount, along with patches of hair loss from moth infestation. There are also small dots present throughout that are moth frass (excrement).
F. Ritchie/© AMNH

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Preventive Care Strategies for managing Pests
CCI Agents of Deteriorati on: Pests

Physical Forces

Physical forces act on museum collections in swift and disastrous ways, such as human error in dropping an object or a natural disaster that collapses a building, or in prolonged repeated exposure, such as daily touching by the public or vibrations from nearby trains. Deterioration results in breaks, loss, and loose components.

Examples of Damage

View of the underside of a koala taxidermy mount in a display case with a branch. The three visible feet are off the branch.

Example of deterioration from physical force: this koala taxidermy mount was lifted improperly from the display case, causing it to fall off the branch.
F. Ritchie/© AMNH

Taxidermy mount of a field mouse attached to a wooden base. The proper left ear has been crushed and is not in view.

Example of deterioration from physical force: the proper left ear of this field mouse taxidermy mount was crushed when wrapped with plastic sheeting dust cover.
F. Ritchie/© AMNH

Side view of an owl taxidermy mount attached to a wooden perch display base. The feathers on the left side are matted and flattened.

Example of deterioration from physical force: this owl taxidermy mount was not stored standing on the display base, as in the photograph. Instead, the mount was stored on its back and the feathers in that area were crushed by the weight of the mount and appear flattened compared to other feathers.
F. Ritchie/© AMNH

Person wearing a black glove holding the head of a taxidermy purple finch next to the rest of the body/mount.

Example of deterioration from physical force: the head of this cardinal taxidermy mount detached after the storage box was moved and the mount jostled. The skin of bird taxidermy is thin and prone to breaking.
F. Ritchie/© AMNH

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CCI Agents of Deterioration: Physical Forces

Fire

Fire can quickly lead to complete loss of a collection. Even if objects are not consumed by the fire itself, damage can occur from smoke soot deposits, as well as water damage from extinguishing.

Examples of Damage

Two images of a mountain goat taxidermy shoulder mount hung on a wall; the goat on top is dark in color because of a coating of soot, while the bottom goat is clean white with no soot.

Example of deterioration from fire: a mountain goat taxidermy mount covered in dark soot from smoke before conservation treatment (top) and after soot removal treatment (bottom).
L. Nieuwenhuizen/© AMNH

Two images of a lion skin rug stretched out on the floor; the rug on top is dark in color because of a coating of soot, while the bottom is clean with no soot.

Example of deterioration from fire: lion skin rug covered in dark soot from smoke before conservation treatment (top) and after soot removal treatment (bottom).
L. Nieuwenhuizen/© AMNH

A large room full of taxidermy shoulder mounts on the ground, the animals include big horn sheep, mountain goat, kudu, and others. The fur on all the mounts is dark in color from a coating of soot due to smoke exposure.

Example of deterioration from fire: a collection of taxidermy shoulder mounts that were exposed to fire and obtained a discoloring layer of dark soot.
L. Nieuwenhuizen/© AMNH

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CCI Agents of Deterioration: Fire

Water

Exposure to water alone does not often cause extreme or instant damage, in fact many conservation treatments involve water. However, when materials are exposed to large quantities of water at once, such as a pipe burst or flood, it can cause saturation and fragility, soiling, and inhibit mold growth.

Examples of Damage

Close up of a taxidermy elephant trunk. The skin in one area is disfigured and pulling away from the mannikin, exposing white areas.

Example of deterioration from water: the skin on this taxidermy elephant’s trunk was exposed to a prolonged water leak that swelled it and caused it to lift away from the mannikin. Drip marks can also be seen on the tusk.
J. Sybalsky/© AMNH

Kangaroo taxidermy mount in a display case. The hair on the top and body of the kangaroo is matted due to water damage, while other areas of the body

Example of deterioration from water: the hair on the body of this kangaroo taxidermy mount was exposed to a prolonged water leak that thoroughly wetted it and resulted in matted hair once dry.
J. Sybalsky/© AMNH

Close up of the head and neck of a bird taxidermy mount. There are dark streaks running down the white feathers, a result of dirty water dripping onto

Example of deterioration from water: dark streaks on the white feathers of this bird taxidermy mount are the result of dirty water dripping onto the specimen.
J. Sybalsky/© AMNH

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CCI Agents of Deterioration: Water

Thieves and Vandals

Theft can include planned robbery of important or valuable pieces in collections, opportunistic theft by visitors, embezzlement by staff, and vandalism.

A hallway lined with metal storage cabinets. Each cabinet is closed with a padlock.

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CCI Agents of Deterioration: Theft

Custodial Neglect

Custodial neglect occurs when preventive and interventive conservation measures are not taken to protect a collection, such as not correcting improper environmental conditions and using non-archival storage or exhibition materials. Custodial neglect also occurs when objects are disassociated from their records.

Example of Damage

Primate taxidermy mount on a table in a storage room that has a large paper label taped onto the back of it.

Example of deterioration caused by custodial neglect: a taxidermy mount with paper label taped to the back. The label is unsightly and if removed, could cause fur loss from the pressure-sensitive tape.
F. Ritchie/© AMNH

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CCI Agents of Deterioration: Custodial Neglect

Nine of these risks are physical (physical forces, fire, water, criminals, pests, pollutants, light, incorrect temperature, and incorrect humidity) and the tenth is custodial neglect. This tenth agent is most dependent on issues relating to general collections management policies. Risk for all of these agents of deterioration can be controlled at many levels—from the site location, down through the building, room, cabinet, or object.  It can also be controlled by implementation of proper policy and procedures. 

Specimen Handling Checklist

Agents of Deterioration

Learn more about Preventive Conservation