The Preservation Handbook Online

Table of Contents

I. Preservation
II. Assessment
III. Collection Assessment
IV. Agents of Deterioration
V. Monitoring collections
VI. Materials
VII. Storage
VIII. Conservation
IX. Disaster Planning
X. Housekeeping
XI. Resources / Suppliers
XII. Preservation Grants

Monitoring Collections


Collection management means different things to different people. This handbook focuses on managing preservation and conservation of materials in cultural collections. Preservation is most effective when it becomes integrated into your institutional mission. The preservation program requires exact tracking of the different dimensions that will affect deterioration: means of control, object location, and agents of deterioration. By formulating a standard audit sheet, collections can accumulate meaningful data in daily routines that can provide insight into the effectiveness of current control measures. A downloadable example of an audit sheet is located at the bottom of this page. An estimation of deterioration by analysis of preventative measures will help identify high risk areas and items with common susceptibility. Assigning a yes or no to each agent of deterioration on the audit sheet, specific to location, will allow you to scale risk within the collection. For example, if the item being audited is susceptible to three out of five possible agents of deterioration than 60% of the value of that item is at risk. Deterioration occurs in the material world and damage occurs in world of knowledge.

Temperature and Relative Humidity

Daily monitoring of temperature (interior and exterior)along with relative humidity levels is necessary for successful preservation programs. Data should be continually collected and relationships identified for at least one year to account for all seasonal changes and areas needing improvements. "Every collection should have a psychrometer for readings and calibration, a recording hygrothermograph for continuous measurements of temperature and humidity, and a small portable hygrometer for spot checks and case readings. These are basics; additional equipment may be purchased where budgets allow."xxi Monitoring a collection is resource intensive. Equipment types vary in price from fifty dollars on up to the thousands.

Instrument types

Humidity indicator cards - change colors with humidity fluctuations, have a long shelf life, are good for gross measurements and are inexpensive.

Psychrometers - wet-and-dry bulb (sling) and aspiring psychrometers (electric) give true values for relative humidity and temperature. Should be used for instrument calibration, recording daily fluctuations and spot readings. Possibilities for inaccurate readings exist because of operator error, contaminated or ill-fitting wicks and inadequate air-flow from weak batteries. Psychrometers are relatively inexpensive ranging from fifty to two-hundred and fifty dollars.

Hygrometer - instruments that measure but does not record relative humidity. All types of hygrometers lose accuracy and most cannot be re calibrated.

Minimum / Maximum Digital Hygrometers - contain a built in memory function that tracks minimum and maximum temperature and humidity for a twenty-four to forty-eight hour period. Small, accurate and relatively inexpensive.

Hygrothermographs - continually monitor temperature and humidity levels producing cumulative data on graph paper. Hygrothermographs use mechanical or electronic sensors to detect and measure changes in ambient air quality. They are highly sensitive to jarring and deterioration of the human hair bundle used to measure pollutants and changes to relative and absolute humidity. Hygrothermographs need frequent maintenance and re calibration.

Datalogger - measures and stores temperature and relative humidity data for cumulative periods that can be downloaded to a computer and interpreted using proprietary software. Excellent way to amass statistical data for a collection but does not provide instant readings. Datalogger's use electronic sensors to track humidity and will have varying sensitivities.

Things to remember when monitoring relative humidity and temperature

"First, the sensors of most instruments, especially humidity sensors, can be seriously inaccurate, initially or as they age. This means that most such instruments need re calibration. against an instrument of greater accuracy . Second, except for such parameters as artificial lighting that are relatively constant, individual spot readings are of little value and can indeed be misleading."xxii The less automated the equipment the more staff time is involved. The key is to be meticulous and put the data to work. If no conclusions can be drawn from the data or if inaccurate readings are returned, the resources and time invested are wasted. Keep track of outdoor data to evaluate the buffering capabilities of your building. Record power outages to determine rate of ambient change within the building envelope outside of mechanical controls. Most rooms have un-even temperatures. Sensitive items should be located away from problem areas such as HVAC vents and exterior walls. Spot readings for relative humidity should be location specific. Generalizations can not be made and only careful research of climatic conditions, collection materials, and limitations specific to your institution, can a realistic range of temperature and relative humidity be determined.


There are many inexpensive light meters available that provide adequate data for effective monitoring. Your institution should invest in a light meter that reads all types of electromagnetic radiation. When a light meter is not available light levels can be measured using a 35 mm single-lens reflex camera using these procedures:

The "blue wool standards," card measures the total cumulative exposure an object is subject to. Both natural and artificial light can cause damage. Direct sunlight should be avoided since it contains high levels of infrared and ultraviolet radiation. "UV filtered natural light can cause more than five times the amount of damage of an equivalent visible level of incandescent light."xxiv Electrode less lamps and fiber optic lighting are the safest most energy efficient light sources available.


Housekeeping is an excellent opportunity to check your collection for deterioration and signs of infestation. These include insect frass, irregular cosmetic or structural damage, dark spots, fuzzy or slimy fruiting bodies, rodent droppings, and pungent or acrid smells. Collection objects on exhibit are at higher risk to infestation and should be checked once or twice a week. Identifying what type of pests are involved and the degree of infestation is essential in designing a defensive strategy. Traps should be checked daily and potential hot-spots like basements and attics should be examined weekly.

"When insect infestation is suspected objects should be placed on a dark cloth for several days; small holes and very fine sawdust powder are indications of insect presence. Other organics, such as textiles, animal pelts, paper, leather, and feathers, should be examined under strong light using magnification. Such examinations should be conducted four times a year."xxv

Areas that have experienced water damage from leaking roofs, broken pipes and flooding should be inspected for early detection of mold growth. Often there will be no easily visible signs. Tachybotrys Chartarum: the toxic indoor mold (2000), is a comprehensive resource for history, identification, and response to toxic mold infestations.


No reliable literature has been produced regarding the effectiveness of filtration systems outside of proprietary companies. These studies may be unreliable as they represent commercial endeavors. Government agencies are generally the only organizations large enough to support the cost of monitoring air quality. These agencies focus on outdoor air to monitor and control pollution on a macro level. Continuous monitoring would be cost inhibitive and not realistic in museum, archival, or library settings. There are "spot determination" test kits available that are reasonably priced and provide accurate information. Most of these kits test for Ammonia, Carbon Monoxide, Chlorine, Hydrogen Sulfide, Sulfur Dioxide, and Nitrogen Dioxide.

Gas Chromotography (GC) can be used to detect toxic gases through photoionization. The cost of purchasing a GC can be offset by having multiple cultural and historical institutions invest in the purchase. For product suppliers, look in the resource section of this site.


Carefully monitoring reactivity is important for composite objects. Objects made of multiple materials experience compounded deterioration. Actively degrading objects should be isolated from other pieces. Identifying and stabilizing the weakest material of a composite object will determine environmental needs. Familiarity with a wide variety of materials and their interactions will prevent storage mishaps that might accelerate object deterioration.


Humans pose the greatest risk to cultural material. Damage can occur through mishandling, ignorance, and malice. Every person that physically interacts with collection objects should be trained in preservation principles and safe handling procedure. Staff and volunteer training should be an ongoing process to ensure participation and commitment to the preservation program.

Security needs should be assessed and solutions implemented. User restrictions should be established to ensure object safety when examination is taking place. Allowing only pencils and single sheets of paper into reading rooms reduces risk of damage and loss. Lockers to store belongings in such as backpacks and brief cases should be installed for patron convenience Instituting a patron id system is helpful in maintaining ethical treatment of cultural property. Reading rooms and patrons should be easily observed. Display items are safest when physical barriers such as glass cases and exhibit boxes are used. Only staff should have access to storage and processing areas.


Environmental monitoring is tedious and must be undertaken by people that understand the cause and effects within the system. Rote recordings of isolated spots within a collection can paint an inaccurate picture. Sampling the conditions also provides limited overview and therefore must be done with high accuracy to ensure validity. Environmental conditions will vary according to season, weather, time of day, mechanical equipment serving the space, zone monitored, and use or non-use by people. Data will need to be analyzed to identify trends and problem areas. Using database programs, like Access, or statistical software, such as SPSS, will help accurately interpret and bring meaning to the numbers.


XXI. Craddock, A. B. (1992) Control of Temperature and Humidity in Small Collections. In K. Bachmann's Conservation concerns. Washington: Smithsonian Institution Press. (pp.16)
XXII Banks, P. N. & R. Pilette. (2000) Environment and building design . Preservation issues and planning. Chicago: American Library Association. (pg. 138)
XXIII Weintraub, S.. (1992) Creating and maintaining the Right environment. In A. W. Schultz (ed.), Caring for your collections. New York: Harry N. Abrahms Inc.
XXIV Taken from "Using a camera to measure light levels" (1992) CCI Notes 2/5, Ottawa: Canadian Conservation Institute.
XXV Hunt, V. R. (1992) Composite objects: Materials and storage conditions. In K. Bachmann's (ed.) Conservation concerns. Washington: Smithsonian Institution Press. (pp. 130)