Cleaning Exhibit Cases

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Keeping the exterior of exhibit cases clean is a part of routine exhibit maintenance. Cleaning the interior surfaces of a case requires special conservation precautions.

What precautions need to be followed when cleaning exhibit cases?

Removing dust, fingerprints and other marks from the exterior of an exhibit case poses only a limited threat to the objects displayed inside. The build-up of static charge can, for example, lift up pages of an open book. Vibration from wiping the case may stress mounted objects. Such concerns can be addressed with proper materials and techniques. Cleaning the interior of an exhibit case, on the other hand, exposes the objects to a wider range of potential damage; both physical and chemical. Cleaning the interior of a case should be limited to:

• long-term displays;
• areas of high visitation, especially when particulate filtration is poor;
• periods between changing exhibitions.

Good planning anticipates and eliminates much of the risks involved in cleaning case interiors. Use the conservation-appropriate techniques and materials outlined in this TechNote as the basics of case cleaning. Whenever possible, combine cleaning the case interior with another task that requires opening the case, such as rotating an object off exhibit. Note that cleaning collection objects is clearly a distinct responsibility from case maintenance. Refer to your museum’s own policy for cleaning objects on display.

• Understand the construction of the case before starting. The maintenance manual should include drawings and instructions for opening the case. This work often requires more than one worker. Be sure that the case is reassembled correctly, including the relocation or replacement of gasket materials and all fasteners.
• Be aware of, and try to reduce, any vibration translated to the objects when opening or closing the case.
• Consider whether it is safer to leave objects in place during cleaning, or to remove them from the case. This will depend on the case construction as well as the objects. Objects that might be left in place include those on intricate mounts or that are away from the surface(s) to be cleaned. Objects susceptible to vibration or objects that may be bumped during the cleaning process must be removed. Curatorial staff usually handle the objects, placing them on conveniently located carts or tables.
• Clean cases during non-public hours. An open case is a security risk that must be monitored by staff.
• Avoid opening a case during times of high or low humidity. This is especially important for environmentally controlled cases because the objects will be affected by exposure to different environmental conditions.

What methods can be used to clean the interior surfaces of a case?

The interior surfaces of the case—including glazing, graphic panels, box mounts and shelves, base and side panels—may collect dust that needs to be removed. Conservation-appropriate methods for routine maintenance do not use any type of "cleaner" in order to avoid chemicals that might damage the objects.

• Dusting with a soft, dry cotton cloth (such as cotton diaper fabric) may be useful for many surfaces including painted dry wall or wood and laminated surfaces. Turn the cloth frequently, presenting a clean face with each pass so that dust on the cloth does not abrade the surface. When a static charge develops on the surface, dampen the cloth slightly with de-ionized water. Alternatively, use a cleaning cloth such as Dust Bunny Magnetic Wiping Fabric by DuPont. This combination of Tyvek and nylon attracts dust through a combination of low electrical conductivity and high surface area.
• Vacuuming with a soft brush attachment and the unit set at low suction is very effective at removing dust from exhibit cases. Vacuuming prevents abrasion of surfaces and is effective at removing dust from textiles used as case liners. Always use a small attachment with a hose long enough to reach surfaces. (The vacuum motor must remain outside of the exhibit case.) For surfaces that are marked by the pass of a vacuum brush, use a soft, hand-held brush to direct dust into the vacuum suction. It is advisable to use a vacuum cleaner with a high efficiency particulate filtration system. Such HEPA units trap small particles that are exhausted by ordinary filters. See TechNote 1:13 for more detailed information on HEPA units.

What is the best method for cleaning glass and plastic glazing?

It may be necessary to use a commercial product to clean glazing, especially exterior surfaces marked by fingerprints. Never use household cleaners, window cleaning fluids, scouring compounds, gritty cloths or strong solvents such as alcohol, acetone, ammonia, carbon tetrachloride, etc. to clean glass or plastic surfaces. Even small amounts of ammonia or alcohol can result in crazing of acrylic glazing (such as Plexiglas or OP3).
Clean the inside surfaces of a case first since the outside may be marked during re-assemblage. Two rules to follow are: 1) always spray any product you use onto the cleaning cloth, not onto the case surface and; 2) always let solvents evaporate before closing an exhibit case. Otherwise, harmful vapors can be trapped inside the case environment.

• Clean glass with a cotton cloth slightly dampened with de-ionized water. A small amount of alcohol may be added to the water.
• Dusting plastic glazing with a dry cloth creates static electricity that attracts more dust particles. When this happens, use special anti-static cleaners such as Plastic Clean & Shine, or "Kleenmaster Brillianize".

Can frame glazing be cleaned in a similar way?

It is important that the frame package be well-sealed so that the interior glazing surface does not require frequent cleaning. Although the methods discussed above can be used to clean the exterior surfaces of glazing, it is very important that only a limited amount of cleaning product be used, and that the product never be applied directly to the glazing but to the cloth instead. This is because the frame package creates a wicking mechanism that can draw liquids into the frame interior, thus exposing the paper, textile, photograph or other framed object to harmful liquids or vapors. The frame itself can be dusted with soft brushes or with vacuum suction. Do not use any water or commercial product on the frame unless recommended by a conservator or the frame manufacturer.

Products, Manufacturers and Suppliers

Mention of a product, manufacturer, or supplier by name in this publication is for information only and does not constitute an endorsement of that product or supplier by the National Park Service. Listed materials have been used successfully in past applications. It is suggested that readers also seek alternate product and vendor information to assess the full range of available supplies and equipment.

1. Dust Cloths - diaper cloth, terry cloth, linen: available at local fabric stores

DustBunny, Magnetic Wiping Cloths

Test Fabrics Inc.

2. Acrylic Glazing Cleaners

Kleenmaster Brillianize

Read Plastics

Plastic Clean & Shine #1

Novus INC.

3. High Efficiency Vacuum Cleaners

(see TechNote 1:13)