Achieving an optimal environment is critical for collections to survive. There are 9 basic areas that should be monitored and addressed on a regular basis.
Agents of Deterioration
- Physical Damage – Cumulative or catastrophic, physical damage alters an object. There are five force-related effects: impact, shock, vibration, pressure and abrasion. Setting up control measures can be beneficial for preventing physical damage. Catastrophic events, such as earthquakes, should be included in emergency response plans. Cumulative damage can be difficult to determine, but should not be overlooked. Establish procedures to protect items from damage caused by vibration or abrasion.
- Thieves/Vandals – Theft and vandalism can be intentional, opportunistic or malicious. By creating a security procedure, artifacts can be kept safe.
- Fire – Fire is the most destructive and immediately damaging source of deterioration. A fire can be catastrophic and damage artifacts past the point of recovery. Surviving artifacts still can be damaged by heat, soot and ash. Determining a museum’s vulnerability to different events that cause fire can allow for appropriate mitigating procedures to be put in place.
- Water – Water damage can be caused by a variety of events: weather, roof leaks, plumbing, spills, firefighting and even accidents. Water causes organic materials to swell, stain and discolor artifacts, weaken hinges and mounts. Plumbing leaks can deposit sewage and other contaminants on items. It also provides the environmental conditions that produce mold and rust. Keep track of necessary maintenance to avoid building related leaks. Create an emergency response plan specifically for water-related events.
- Pests – Microorganisms, insects and rodents are a majority of pests affecting artifacts. Continually monitoring of a collection should alert staff to potential pest issues. Design an Integrated Pest Management (IPM) program to eliminate and prevent pests.
- Temperature and Relative Humidity (RH) - Materials break down if exposed to inappropriate levels of temperature and relative humidity. Generally speaking, the higher the temperature, the faster objects will deteriorate. Similarly, high relative humidity can cause harmful chemical reactions. A combination of the two can encourage insect activity and mold growth. Conversely, low relative humidity can cause embrittlement or desiccation. Install climate controls to slow the deterioration of materials, and maintain a temperature no higher than 70 degrees and a stable relative humidity between 30 and 50%.
- Light – There are 3 types of light that can damage artifacts; ultraviolet, visible and infrared. All damage caused by light is permanent and cannot be reversed.
- Ultraviolet (UV) rays are extremely damaging to most materials. Fibers become brittle and can yellow. UV light can also fade dyes and change colors. UV filtering film, drapes or shades on windows will cut down UV from sunlight. Placing UV filtering sleeves over fluorescent lights can block most harmful rays. Exposure time can be reduced in storage areas with timed switches or a "low light" policy.
- Visible light can also damage your artifacts. While there are filters and other ways to limit UV exposure, visible light, is unavoidable. Light levels should be kept as low as possible while still enabling visitors to view objects on display. It is recommended that levels range from 5 to 15 foot candles, depending on sensitivity. Limiting the amount of time items are exposed to light is also important. Plan your exhibits so that items can be rotated and returned to dark storage to prevent fading.
- Infrared (IR) light is a common source of radiant destruction because it creates heat. Heat can cause cracking, lifting and changes in an artifact’s color. IR heating typically becomes an issue with two sources of light: high intensity (over 465 lux) incandescent lamps and direct sunlight. By limiting visible light, IR will also be limited. Monitoring temperature will make assessing IR light easier.
- Pollutants - Poor air quality and other pollutants can disintegrate, discolor and corrode artifacts. Air quality is a key factor in keeping a collection protected. Make sure air filters are clean, intake vents are not placed near idling vehicles, windows are closed and material is stored in archival-quality enclosures. Archival-quality storage enclosures protect objects from a less-than-perfect environment by slowing air exchange, thereby buffering temperature and humidity fluctuations, cutting down on UV exposure and providing protection against water and other damage.
- Dissociation/Custodial Neglect – This is the only agent of deterioration that does not cause physical damage. Dissociation results in the loss of objects or object related data, or the ability to retrieve or associate objects with data. This affects the intellectual, cultural and legal aspects of an object. By maintaining meticulous records and establishing a procedure for labeling of objects, the effects of dissociation and custodial neglect can be dramatically diminished.
All museums and archives should assess the risks to their own collections. This information is meant to be informative and is not comprehensive.
For More Information
Agents of Deterioration © Canadian Conservation Institute
Know Your Space: Find the Right Environmental Control Monitor