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Collections Preservation Strategy
Copyright 1997, Marc A. Williams

In the nearly 50 conservation assessments I have performed, and during numerous years as a panelist and field reviewer for the Institute for Museum Services, certain common collections preservation needs have become evident for the vast majority of museums and historic institutions. While these do not apply to every institution, and reordering may be needed for specific institutions, the following list is a good starting point when formulating a collections care strategy. These preservation actions are presented in a priority order that is useful in formulating a collections care plan for most institutions.

1) Begin Relative Humidity and Temperature Monitoring

Every building has unique needs and solutions for control of the RH and T. However, in order to make intelligent suggestions on environmental needs and improvements, the existing environments must be monitored for a continuous period of at least a year, and preferably ongoing. This monitoring process allows intelligent steps to be taken in controlling the collection's environments. The data will contain signals of whether dehumidifiers are needed and when they need to be turned on; if further conditioning of the air is required; and may serve to point out problems with drainage, leakage or water infiltration before they would otherwise be noticed. Otherwise, environmental control efforts are just guesses, with no way of determining if the desired effects are actually occurring.

In general, inexpensive manual monitoring systems require more human involvement than high-tech automated ones, which require more money. Therefore, if staff time is available and money is not, begin with a manual system (Inexpensive Monitors) and seek funding for a less labor-intensive system in the future. Take manual readings in each area that contains (or is projected to contain) collections in storage or exhibition. Normally, this would be one in each separate room. It is also helpful to take a reading outside the buildings to record the exterior conditions and to note where the readings are taken in each room.

A complete year of records allows intelligent steps to be taken in controlling the collection's environments. For this reason, assembling the readings should not be taken as an exercise in record-keeping. Rather, the readings must be examined and compared, and used as the basis for decision making. They are probably the most important tool to be used in the preservation of the collection, and, in fact, for the preservation of the building itself.

Readings obtained from monitoring instruments must be analyzed. If desired, an outside consultant can be contracted for assistance.

2) Conduct a Collections Assessment

A conservation assessment, also called a general conservation survey or collections assessment, is a broad, relatively shallow examination of virtually all areas affecting collections preservation (What Is A Conservation Assessment?). Usually, it is conducted by a collections conservator and culminates in a written report. The general goals of an assessment are:

  • Prioritize overall collections care goals;
  • Assist in the development of a long-range preservation plan;
  • Identify simple, immediate steps to reduce collections deterioration;
  • Integrate the needs of the collection with the needs of a historic structure;
  • Identify objects that need immediate stabilization treatment;
  • Educate staff in storage needs, routine maintenance, environmental monitoring and control, etc.;
  • Allow increased funding of preservation, including grants from sources such as the Institute of Museum and Library Services.

    By utilizing a conservation assessment, a your museum can identify its most pressing needs and design a reasonable plan of meeting them. The methods and pace of meeting these needs can be carefully tailored to your specific circumstances.

    3) Have an Architectural Assessment

    If your building is historic, a collections assessor most commonly works in tandem with an architectural assessor, who does a similar examination for the needs of the historic structure. These two consultants must work synergistically, as often buildings and collections have conflicting needs.

    4) Increase Collections/Building Care Funding

    The funds allocated to collections care at most institutions are not sufficient. Unfortunately, at this time, nearly all sources of funding are becoming more difficult to obtain. Nevertheless, it is certainly worth the effort to investigate local and national funding sources. One source to consider immediately is the Institute of Museum and Library Services's (IMLS) Conservation Project (CP) Support Grants, which award up to $50,000 per project per year. IMLS can be contacted at: 1100 Pennsylvania Avenue, NW, Room 609, Washington, DC 20506, 202-606-8539. However, without first having a Collections Assessment establishing priorities, your institution's likelihood of success in obtaining such a grant is nearly zero.

    5) Perform Emergency Treatments

    While, generally, limited collections care funds are better spent for more global preservation needs, objects that are in grave condition may need emergency stabilization treatment. Ideally, do not conduct full treatments on these items, but only place them in a preservation state that will hold them until after more far-reaching needs have been funded.

    6) Improve Drainage

    At most historic sites, the primary source of moisture infiltration into the building is the run-off from the roof, with a lesser amount of run-off from the ground surrounding the building. Often, the earth near the foundation has built up over time due to composting of plant matter to act as dams that prevent natural flow of run-off away from the building. Dammed-up water either overflows at the low points into the building or soaks into the ground, much of which enters the basement or crawlspace. Occasionally, the naturally- occurring drainage of the site is towards the building, rather than away from it.

    The first step in moisture control is to create drainage that flows away form the building foundation. Usually, this can be achieved by relatively minor grading of the earth near the foundation to provide a positive slope away from the building on all sides. Occasionally, when the natural slope is not conducive to good drainage, swales must be formed to direct the run-off away from the structure.

    Even with the best grading, some water will soak into the ground and enter the crawl space or basement. Whether or not this is an acceptable level must be determined by environmental monitoring. Installing gutters will greatly reduce the amount of water that must be carried away from the foundation. They are crucial if proper grading does not exist. Additionally, gutters can be installed quickly and at relatively minor cost. Be sure to regularly clean the gutters. Write this into the routine maintenance plan for the building.

    An alternative (which probably will not be necessary if gutters are installed and site drainage improved) is to install perimeter drains around the exterior of the foundation. Generally, these consist of two separate drains, one near the surface that handles roof/gutter runoff and one near the bottom of the foundation that handles water that soaks into the ground. Often, these are tied to a storm sewer or drywell constructed for this purpose. A carefully installed water barrier is laid against the foundation and beneath the lowest drain to prevent water access to the basement or crawl space. This project requires a significant amount of excavation near the foundation, probably involving archaeological concerns, and is relatively expensive. However, it may be necessary if the other less intrusive and less expensive modifications are not effective, or are not implemented. Grant funding can significantly reduce the out-of-pocket costs.

    7) Initiate Major Repairs to Building(s)

    It is self-evident that if the building is falling apart, preservation efforts for collections within it are nullified. If fund-raising efforts are needed to stabilize the building, this action may have to be delayed.

    8) Clarify Policies and Procedures

    In order to prevent misunderstandings and guarantee continuity, it is extremely important that policies and procedures that define the mission of the institution, set parameters for the scope of the collection, and implement collections and building preservation, be written down and shared with all persons who have responsibility for the buildings and collections. These include not only board organizational decisions, but also collections care practices. Specific policies and procedures should include as a minimum:

  • a) Mission Statement or Statement of Purpose. This clarifies the purpose of the organization and focuses efforts of the board and staff.

  • b) Collections Management Policy that outlines all policies and procedures that affect the collections, including accessioning, deaccessioning, loans, storage procedures and collections preservation.

  • c) Procedures for dusting and routine cleaning by housekeeping personnel. What materials to use for dusting; how to handle objects; what specific objects cannot be dusted safely; where a vacuum can and cannot be used, etc.

  • d) Procedures for cyclical maintenance of collections, including necessary frequency. Materials and procedures for polishing and coating metals, if done; cleaning of items that cannot be dusted; unpacking and inspecting of stored objects; what can be done by volunteers/staff and what requires a conservator, etc.

  • e) Procedures for environmental systems and controls. Keeping shutters/curtains closed to control light; necessary procedures for controlling relative humidity; winterizing procedures, etc.

  • f) Procedures for monitoring of the environment and routine inspection for signs of deterioration of the collections.

  • g) Procedures for regular inspections of the tightness of the building envelope, including windows, doors, paint, weatherstripping, roofs, etc. and repair of small problems before they become troublesome.

  • h) Procedures for cyclical building maintenance, including exterior painting, window repair, repair/replacement of roofs, etc.

  • i) Guidelines for selecting collections care specialists and conservators, as well as contractors to perform routine maintenance and building repairs. Use of qualified, professionally competent consultants and contractors only.

  • j) History of changes to, and restoration of, the building. The history of much of this work may be primarily oral.

  • k) Building maintenance history which documents all products, contractors, vendors, product warranties, and expected service life spans. This is essential in order to assess the performance and deficiencies of products and repairs.

    9) Tighten the Building Envelope

    In order to achieve any type of environmental control, the building envelope must be as tight as possible. The greater the amount of air exchange with the outside, the harder systems will have to work to control the environment, and the less efficient passive buffering systems will be. Keep windows and doors closed. Consider the use of storm windows and doors. Install weatherstripping. Insulate access holes for wires and pipes. Close fireplace dampers and consider capping chimneys. A tight building envelope may allow the use of a simpler environmental control solution, and is certain to save you money in utility costs.

    10) Reduce Light Levels

    In virtually all institutions, light levels are too high. Light destroys the natural or maker- applied colorants in wood, dyes, finishes, paints and fabrics. Textiles and paper are weakened, possibly to the point of disintegration. In severe cases, light can degrade the cellular structure of wood. All of these changes are irreversible and permanent. The amount of damage from light depends upon the wavelengths of light present (sunlight has them all), the intensity of the light and the length of exposure. Reducing any or all of the three will have benefits. However, only total darkness will eliminate the threat of light damage. Therefore, light control can be facilitated by eliminating the most damaging wavelengths (UV, violet and blue), reducing the intensity as much as possible and shortening the length of exposure.

    The goal of light control is to eliminate all of the UV and reduce visible light levels to less than 150 lux (50 lux for extremely sensitive items). When buildings are not open for visitation (e.g. mornings and evenings, as well as holidays and during the winter), exhibition areas should be completely dark. Storage areas should be dark all the time. Clearly, the control techniques chosen must integrate with the aesthetic interpretation of the buildings. However, it is important not to let such issues become a stumbling block for doing something to control light.

    Control of light can be accomplished in several ways. The simplest is to block off the windows in an exhibition or storage area. This can be done with solid panels, black-out cloths, shades or shutters. It is especially important to exclude direct sunlight, although indirect light is still highly dangerous.

    A second technique is to reduce the intensity of the light by filtration. This involves the application of a film or plastic sheet to the window or its opening that filters or reflects a large percentage of the light, in essence acting as sun glasses for the window. A third option that is related to this is the filtration of the UV component of the light. This can be combined in the same film or sheet as intensity reduction. A final method is to remove all light-sensitive objects from areas or rooms that are too bright.

    It is important to keep light levels throughout the building uniformly low. In this manner, the visitor's eye can adjust to the lower level. If levels alternate between low and bright, the human eye cannot adjust quickly enough to the changes and visibility will be impaired greatly. In addition, the visitor is often looking towards a window when in a room. Lower light levels at the window will reduce the blinding effect, and actually allow the room contents to be seen more clearly.

    11) Review Accessioning/Deaccessioning Procedures When an object is accepted into a collection, it attains a status that is different than it had when in use in the donor's house. It is no longer acceptable to handle the object without taking proper precautions. Certainly, the object can not be used. Proper display and storage must be provided to the object, as well as competent conservation care when required. In essence, each object must be placed on an imaginary pedestal and granted a unique and special status. This applies to all objects, regardless of their economic value, cultural significance or aesthetic beauty.

    Preservation of the collections is a legal custodial responsibility of the institution. Time frames for preservation are hundreds or even thousands of years. This can be difficult to comprehend fully from our current societal perspective of planned or natural obsolescence, where an object's lifetime may be only a few years. Therefore, mental adjustments may be necessary to allow future generations to appreciate their cultural heritage. It is important that all members of the board and staff recognize this long-term perspective, and the degree of effort required to properly preserve the collections. It is better to correctly preserve fewer items than to allow a larger collection to suffer unnecessary degradation. For this reason, you need to look very critically at your collection, and the policies that determine accessioning and deaccessioning. Bulk storage of deteriorating objects is not responsible collections care.

    12) Evaluate RH and T Monitoring Results

    Once a minimum of one year's monitoring data has been collected, it needs to be evaluated to determine current circumstances, and available options to improve conditions. Virtually all institutions can significantly improve existing conditions. If desired, an outside consultant can be contracted for assistance in evaluating data and options.

    13) Make Simple Environmental Improvements

    Historically, the traditional museum temperature standard of 70 degrees F was chosen for human comfort, not for the preservation of the collections. Object "comfort" would dictate control systems based around a fairly stable relative humidity, with the lowest possible temperature. For collections in most temperate climates, a much better set of preservation specifications would be 35%-55% RH with a temperature no higher than 40- 45 degrees in the winter (no heat at all is acceptable), and no more than 90 degrees in the summer (76-78 degrees if air conditioning is utilized). Control of both relative humidity and temperature to narrower ranges requires sophisticated equipment and may cause increased degradation to the building (see Low-Tech Environmental Control for more detailed information).

    The most basic environmental control is a tight building envelope without any mechanical systems, including no heat. While no alteration of the environment is possible, long-term variations of the naturally occurring interior relative humidity are somewhat limited. It is unlikely that the RH will fall below 35%-40%, although highs may reach 90%. This is greatly preferable to the typical heated-only environment, which often will have a 5% to 90% RH range. The temperature range in an uncontrolled interior environment is likely to be about 10-90 degrees F, varying somewhat with the geographical location. However, temperature fluctuation has a relatively minor impact on museum collections. This uncontrolled temperature range of 80 degrees F would have roughly the same effect as a RH range of only 13%.

    The first step to improve an uncontrolled environment would be to add dehumidification in the late spring, summer and early fall. If properly installed, this would limit the high end of the RH range during warmer weather to about 55%. With the exception of a few times in the winter when the RH is too high, most of the year RH levels would be between 35% and 55%. Thus, a vastly improved environment can be created with only a dehumidifier, with very modest equipment or utility costs. Be sure to install the dehumidifier to allow it to drain automatically, or rapid fluctuation of RH may occur when the unit shuts off because its container is full.

    For the safety of the collections, it is best to segregate human use areas, such as offices or libraries, from collection areas. If possible, these should be in different buildings. If collections and people must share the same building, segregate them by floors, ideally with the human use spaces above the collections spaces (since heat naturally rises). In this manner, the lower level collections rooms can be kept cooler in the winter, with a resulting higher relative humidity. Try not to be tempted by the appeal of heating for visitor comfort. If it is cold enough outside to turn on the heat, visitors will be wearing appropriate warm clothing. Additionally, it is preferable for visitors to keep their coats on to minimize damage from carried coats banging into collection objects.

    During this time, plan for more sophisticated, permanent solutions to environmental control. Often, these require fund raising to allow their implementation.

    14) Consider Storage Improvements

    Numerous specific improvements can be made to your individual storage conditions. These should be detailed in your Collections Assessment. One general option to be considered is a room-within-a-room storage space (Room-within-a-Room Storage Improvement). A free-standing room that incorporates tight construction, heavy insulation, vapor barriers, no windows, and a moisture-absorbing material on the interior walls is constructed inside an existing room. The room is built so that it does not touch the walls or ceiling, which allows air circulation around it. Therefore, no damage is done to the architectural character of the original room.

    While conditions outside the room will still vary on a daily basis, inside the room, relatively little change will occur. Seasonally, there will be a gradual temperature shift, but the relative humidity should remain within a fairly narrow range, provided that the space containing the room-within-a-room is not heated. This reasonable level of control is accomplished without the use of any mechanical systems. Obviously, proper HVAC system design and installation can improve further upon the passive control methods.

    When designing and installing storage furniture, the nature of the materials used for the supports, shelving, and cases is very important for collections preservation. A very good basic treatise on this subject is found in the book Conservation Concerns: A Guide for Collectors and Curators, pp. 23-28. General suggestions for storage follow:

    a) Stacking of objects is not recommended. If absolutely necessary to do so, a padding material, thin Ethafoam (1/8" polyethylene foam), should be placed between objects. Objects must not be too closely packed, touching neighboring objects. This can lead to abrasion damage.

    b) Collections items should be raised off the floors at least 3" and ideally 6" (minimum 6" for basements). In the event of a disaster, including water from firefighting, considerable damage can be avoided if the bottoms of objects are not sitting in a pool of water.

    c) Pad beneath items on shelves. 1/8" Ethafoam works well and comes in long rolls of appropriate width. Try not to crowd items, and do not stack them unless they are adequately strong and are padded between items.

    d) Closed metal storage cabinets are suggested for the glass, ceramics and other breakable items. Pad the shelves with 1/8 inch Ethafoam or another suitable material. If items are stacked, pad between each piece with Ethafoam or several layers of tissue. Bolt the cabinets in place so they will not fall over in the event of an earthquake or other vibration. If open shelving must be used, install a 1" high lip on all shelving edges to prevent items from "walking" off the shelves.

    e) Light-weight polyethylene dust covers should be placed gently over unprotected items in storage. They can be ordered in sizes as large as sofa size and used to cover a number of collection items at once. Items on open shelves should be covered individually, or alternatively, entire shelving units can be protected.

    f) Framed items in storage should be grouped together in vertical storage with separator pieces of mat board or acid-free cardboard between the frames.

    g) Quilts, coverlets, rugs, and other large, flat textiles should be stored horizontally on a rolled rack. Carpet tubes covered with polyethylene or Mylar, followed by acid-free tissue, will work well for support. Place a dust cover over the rolled textiles.

    h) Use acid-free boxes for sensitive items stored in boxes. Do not crowd objects and use padding between items. This is especially true of textiles.

    15) Conduct Item-by-Item Collection Surveys

    Engage consultant conservators to conduct item-by-item surveys of collection items. This will allow specific recommendations on collections care to be made, as well as allow prioritization of treatment needs. Usually, surveys are done by a team of conservators with specialties that match the needs of the institution. For example, a furniture conservator, paper conservator, objects conservator and textile conservator may be an appropriate team.

    16) Implement More Sophisticated RH and T Control

    Design and installation of mechanical environmental control systems requires careful, thorough planning. At the very least, you should include a collections conservator and an HVAC engineer in the planning process. If your building is historic, an architectural assessor is highly recommended as well. It is surprising how many poor decisions are made because a conservator is not involved in planning. Often, incorrect specifications are chosen, inferior control systems are utilized, equipment is improperly sized, or the conflict between the needs of the collections and the needs of the building are ignored. Surprisingly, in numerous instances, the system designed by a well-assembled team will actually be less expensive.

    17) Evaluate Pest Issues

    To help prevent insect access, keep doors and windows closed. Proper weatherstripping must be installed on the windows and doors, including their tops. This should be inspected on a regular basis, and necessary repairs made immediately. Apply fine screening to air intakes, stuff gaps where pipes penetrate walls and close other access points. Also recommended is intensive vacuuming of floors. Be sure to reach corners and other harder to reach areas. Inspect objects regularly in both exhibition and storage for signs of infestation and damage.

    Most institutions do not have a written integrated pest management (IPM) program. While there are more urgent priorities, one needs to be created eventually. If desired, a specialist consultant can be utilized to design the program.

    18) Disaster Plan

    The risk of a disaster is ever-present. In most areas of the country, earthquakes are a realistic possibility. Floods, especially in basements, are common. Hurricanes are a concern in many areas. Fire is always a risk, and even if one is discovered early, saving consumption of the building, the damage from water can be devastating. For these reasons, a workable disaster plan for your collections is necessary. Included should be procedures to implement in the event of an approaching disaster, such as covering windows and moving objects, as well as recovery procedures that allow for safety to persons and the collections.

    Plans must be laid in advance for extra personnel in the event a disaster actually occurs, especially conservators, as well as necessary supplies. Emergency funding also must be planned. Specific duties must be assigned to each staff person, and drills held to guarantee effectiveness. Actual disaster conditions may be much worse than expected, so smooth coordination of efforts is critical. Sample plans are available from other institutions or from the American Association of Museums. Additionally, the Southeastern Registrars Association has written Steal This Handbook! A Template for Creating a Museum's Emergency Preparedness Plan (c/o Michelle McKee Baker, South Carolina State Museum, P.O. Box 100107, Columbia, SC 29202-3107). While there are higher priorities, creation of a disaster plan should not be forgotten.

    19) Begin Treatment of Lower-Priority Collections

    Begin a treatment program for those objects most in need as identified in the item-by-item collection surveys. The goal is to bring all items up to a minimum stable condition. Thus, future treatment needs generally can be of a more modest "maintenance" nature. Emergency treatments of actively degrading objects should be done as an earlier priority as required.

    American Conservation Consortium, Ltd.

    American Conservation Consortium would be pleased to assist you with any aspect of collections preservation, from Collections and Architectural Assessments, to environmental monitoring and control, to storage improvement, to IMLS grant preparation, to conservation treatment of wooden objects, horse-drawn vehicles, painted wood, and architectural features. Please see one of the following links for more information.

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