Ten Agents of Deterioration
Developed in the mid-1990s the agents were first published by Stefan Michalski in 1990 (they were later expanded with the addition of the final agent by Waller in 1995), the 10 Agents of Deterioration define the main forces acting on objects to cause deterioration.
Deterioration can be physical (such as a ceramic breaking) or chemical (ex. metal corrosion), be sudden (ex. destroyed in a fire) or occur over time (ex. gradual embrittlement at incorrect temperatures).
Object vulnerabilities to each agent vary depending on the material itself, and the likelihood and extent of an event occurring. Risk analysis provides a methodology for determining which agents pose the most significant risk for a specific collection; this information can then be used in preservation planning to implement appropriate monitoring and mitigation strategies.
Inherent vice is a related concept, by which objects deteriorate due to the incompatible or unstable nature of the materials of which they are made.
The Ten Agents of Deterioration
Main article: Physical Forces
Examples of damaging physical forces may include those that are fast and catastrophic including both natural disaster and human error (such as earthquakes, or bumping or dropping an object), or slower acting with minor but repeated opportunity for damage (such as improper handling during research and educational use, or vibrations from nearby construction).
Thieves, Vandals, Displacers
Main article: Thieves, Vandals, Displacers
This includes, Planned theft by someone intent on violating the collection, opportunistic theft by visitors, embezzlement by staff, and vandalism.
Main article: Fire
Fire can potentially lead to the quick and catastrophic loss of an entire collection.
Main article: Water Collections storage areas are frequently placed in attic or basement spaces which are most vulnerable to water damage in the event of a roof or plumbing leak, sprinkler system malfunction or flooding.
Main article: Pests
Pests encompass both rodents and insects. Some also consider mold/mildew/fungi to fall under this category.
Main article: Pollutants
Pollutants can be generated both and outside and inside buildings. Many pollutants known to cause human health problems can also cause damage in collections. The two general types of pollutants that contribute to the deterioration of museum collections are particulates and gasses. These can be airborne or transferred by direct contact.
Main article: Light
Damage from radiation (visible, ultraviolet, or infrared), which is cumulative and, once sustained, irreversible, is a function of light intensity (in lux or footcandles) times length of exposure.
Main article: Incorrect Temperature
The detrimental effects of incorrect temperature (either too high or too low) are often observed after considerable time has passed and so the slow deterioration that results is often underestimated.
Incorrect Relative Humidity
Main article: Incorrect Relative Humidity
Organic materials all contain moisture; they absorb and give off moisture and try to find a balance between their moisture content and that in the air around them. If the relative humidity (moisture content) in the air goes up, they will absorb moisture and swell, and if it goes down, they will give off moisture and shrink. If this occurs slowly and moderately then no damage will be caused. However, sudden, large and frequent relative humidity fluctuations can cause shrinkage, warping, splitting, and general aging of objects made of organic materials. A sudden increase in relative humidity can cause condensation on metal artifacts, which will promote corrosion.
Custodial Neglect & Dissociation
Main article: Custodial Neglect
One type of custodial neglect occurs when active care is not taken to preserve the collection or when information and practices on collections care are not current. The second type of custodial neglect is the disassociation of collection objects and their records.
This website, run by the Canadian Conservation Institute, has extensive information on each of the Agents of Deterioration, including understanding the potential sources and effects, as well as possible control strategies (avoid, block, detect, response, recover/treat). It also provides vignettes (case studies) and additional references. A French version of this resource is available.
This online community serves smaller cultural institutions in caring for their collections. They have regular live webinars on a wide range of topics, as well as archived ones on many of the Agents of Deterioration. A Discussion forum allows members to post questions and receive responses from moderators as well as others in the field. There is also a Resources page that includes a search option by “Risks to Collections”; each of the Agents pulls up links to numerous websites for further information.
Chapter 4 of the National Park Service’s Museum Handbook covers the “Museum Collections Environment”. The beginning provides a good overview to the Agents of Deterioration, and subsequent sections cover temperature and relative humidity, light, and dust and gaseous air pollution. Figures at the end provide example records for monitoring, and specific guidance, such as using a psychrometric chart and types of materials considered safe for use.
The Indiana Historical Society developed a graphic novel, “Deteriora and the Agents of Destruction” to provide a fun and informative introduction to the 10 Agents of Deterioration. Each of the eight chapters can be downloaded individually.