Creating Natural and Architectural Settings within Exhibits

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Recreating natural and architectural settings within exhibits serves aesthetic and educational purposes. Careful selection of the materials used in such recreations is critical to exhibit conservation.

What are the conservation concerns in recreating environmental settings?

This TechNote discusses conservation issues involved in creating either natural or architectural settings within an exhibit. One setting may include both natural history and architectural features; for example a street scene may incorporate building facades with dirt paths, trees and grasses. Note: Although many of the points are applicable, this TechNote does not deal with historic house museums, zoos, botanical gardens or similar installations incorporating live plants and animals.

Issues affecting collections included within or located near natural history and architectural settings are:

• choice of stable materials;
• staging of the construction;
• potential for insect infestation;
• increased fire hazards;
• housekeeping burdens;
• choice of materials with good longevity.

What types of materials are appropriate for use in exhibit settings?

Above all else, choose stable materials. The diverse materials used in recreating architectural set- tings must not present health risks, must not outgas chemicals harmful to collections, and must retain their shape and strength over time.

1. Health hazards include:
   • pressure-treated wood containing toxic reagents;
   • older siding materials or insulation containing urea-formaldehyde, asbestos or lead paint;
   • natural history specimens treated with arsenic, mercury or other dangerous compounds.
2. Avoid materials with high levels of outgassing or other contaminates unless the choice of other materials would be historically inaccurate.
   • Avoid using any form of an unstable material. For example oak as timbers, unpainted boards, or shavings; or rubber-based plastics in adhesives, molded products or flooring materials.
   • Become aware of unexpected problems by talking with others and researching materials. For example, knot holes in pine boards and conifer branches can extrude pitch.
   • Pay special attention to using inert casting resins, plastics and foams. Do not use large amounts of unstable polyvinyl chloride or polyurethane;
   • Physically isolate collection objects from any suspect materials that are used.

What is meant by selecting materials that age well?

Choosing materials that age well under the anticipated traffic load prevents disruption of the exhibit for premature refurbishment. Recreated settings that the public walk through must hold up to the foot traffic. Architectural features that support collection objects (hung on walls, in cases on walls or set into walls or windows) must have enough structural integrity to remain vibration- free.

• Consolidate earthen pathways prior to opening the exhibit; apply sufficient consolidant for long-term protection. Objects should not be exposed to polyester and urethane resins used for consolidation.
• Premature wearing of flooring material along visitor pathways is a concern. Choose materials rated for heavy traffic and use a product that can be replaced in sections; for example carpet squares as opposed to wall-to-wall coverings or squares of imitation pebble stone instead of a continuous length of consolidated pebbles.
• Materials such as thatch, shingles and moss may become brittle, adding to the dust and debris that tends to collect in such materials. Avoid dried and friable materials.
• Whenever possible, use synthetic botanical specimens, such as silk or wax replicas. Original natural history specimens must be pre-treated before inclusion in exhibits.
• Make sure that all materials are completely dry. Moist botanical materials deteriorate and support mold growth.

When can collection objects be introduced into the setting?

Ideally, all construction will be completed before bringing any collection objects into the setting. Some settings, however, incorporate accessioned collection objects; for example mounted natural history specimens from the collection may be installed in a natural environment recreated with artificial landscape features and preserved plant materials. The following guidelines always need to be followed.

• Apply consolidants to fix friable surfaces such as dirt paths before collection objects are brought into the area, allowing enough time for the resins to fully cure.
• Finish all artificial landscape features and architectural elements before introducing collection materials; this includes all work that produces dust or fine particles and any application of a paint or resin.
• Place collection specimens as one of the last, finishing touches of the display.
• Aerate displays incorporating large amounts of resins or other types of chemicals.

Why are there special concerns about infestation?

Exhibit production staff must be vigilance in guarding against bringing infested materials into the museum. Materials that are a potential source of infestation include:

• natural history specimens, including botanical, biological, and landscape elements;
• wool, feathers, furs, etc. including those found in bedding or used in textile demonstrations;

exterior and interior wall materials, including unfinished timbers, wood and wood composite boards, sod;

• roofing materials, such as thatch and wooden shingles;
• flooring materials, including wooden boards, dirt, sand, pebbles, and earth;
• a wide variety of materials can support mold growth; freeze-dried specimens may rot.

Both old and new materials can be the source of an insect problem.

• Inspect everything; any type of insect is a problem; spiders and ants may not attack collection objects but will attract other insects.
• Fumigate or freeze all materials before bringing them into the building; this kills eggs and larvae that may not be evident. (Mobile truck freezers can be utilized on site.)
• Natural history specimens attract insects; if possible, enclose specimens in a small case or acrylic cube. This is a particularly appropriate measure for rare or endangered species.
• Once the exhibit opens, inspect natural history specimens frequently.

Can water and weather effects be achieved safely in exhibits?

Incorporating water into an exhibit is problematic. A water reservoir elevates relative humidity in the surrounding area and introduces the potential of mold growth in the exhibit. The malfunction of pumps and the clogging of drains are perpetual threats. For such reasons, water effects in recreated settings and dioramas are usually achieved with synthetic materials.

• Plexiglas and Mylar make convincing illusions of water at a low cost.
• When using pourable resins to imitate water effects, allow enough time for the plastic to cure before introducing non-collection objects and make sure that the resin is stable over time. Acrylic resins are preferred.

The appearance of either snow, ice, rain or fog can also be imitated. Consider the following.

• As always, use the most stable resins and plastics; these include acrylics, silicones, polyethylene, polystyrene, and polycarbonate. Allow these materials to cure and the out- gassing to dissipate before introducing collection objects.
• Pourable resins such as clear acrylics and clear or opaque silicone rubbers can be used to imitate snow, ice and rain. Adding a bulking agent such as fumed silica to white silicone rubber gives a consistency useful in imitating snow. Never allow these materials to touch collection objects.
• Plastic-based shredded materials migrate through electrostatic charge. Limit charge build up by using glass glazing as opposed to plastic and wood or tile flooring as opposed to carpeting. If possible, cover the material with fine netting.
• To give depth to displays, use forms molded or shaped of wood, papier mâché, blocks of polyethylene, or other materials. This allows a thin coating of resin or other material to pro- vide the appearance of ice or snow.
• Never apply any resin to an accessioned collection object or to an item that was difficult to locate and therefore will be hard to replace.
• There is no documentation that dry ice (solid carbon dioxide) or liquid nitrogen used to recreate fog has any direct negative effect on collections, as long as they do not touch an object. Both, however, depress the temperature of the surrounding air; locate the reservoir away from collections and do not use the effect near collection objects that are temperature or humidity sensitive.

Why do recreated settings pose additional fire hazards?

Environmental settings pose increased fire risks on a number of fronts. Architectural and environ- mental features that establish vertical airways spread fire quickly and into new areas. Some mate- rials emit toxic gases when burned.

• Avoid selecting highly flammable materials.
• Follow all fire and life safety codes. Plastics, woods, fabrics and other materials used in exhibits must conform to NFPA standards .
• Make sure annual fire inspections are performed and implement any required or recommended changes.
• Know the health hazards in the event of a fire. Lead from paint, arsenic from pressure treated wood, asbestos and all plastics, foams and resins create health hazards when burned. If possible, avoid such materials.
• Record all materials used in the setting. Insure that the list is easily accessible in the event of a fire; give a copy to your local fire station.
• Weigh potential risks of fire against the fire detection and fire suppression equipment in your museum; consider increasing accuracy or response time of detection equipment, as well as installation of suppression equipment.

Will recreated settings increase housekeeping responsibilities?

Recreated settings impose additional housekeeping responsibilities because they are difficult to clean and they produce dirt and debris. In addition to conservation concerns, dusty exhibits detract from the visitor experience and reflect badly on the institution.

• Keep cleaning problems in mind when designing recreated settings. If staff cannot keep these displays clean, enclose the dioramas behind sealed glass-fronted cases or do not install.
• Work out methods to clean displays before the final decisions are made about what types of materials and products to include. Substitute difficult to clean materials whenever possible.
• Vacuuming and forced air blasts may be the best methods to keep displays clean. Purchase needed equipment as part of the exhibit budget. Incorporate special cleaning issues into the Housekeeping and Exhibit Maintenance Plans.
• Dust balls and dead insects that are not removed from corners and inaccessible places are perfect feeding grounds for insects. Undertake a thorough cleaning of all spaces at least twice a year.
• Clean loose materials before bringing them into the museum. Wash pebbles and sand, for example, to remove fine particles, dirt, and insects.
• Covering friable materials such as thatch, sand, and shredded plastics with fine polyester netting contains loose fibers and makes cleaning easier.

When possible, consolidate loose materials such as dirt, sod, or pebbles prior to installation of the collection materials.

Are there any ethical considerations in recreating environments?

The exhibits team does have to consider legal and ethical guidelines when designing environmental settings.

• Botanical and biological displays use preserved specimens: have these reviewed by a knowledgeable resource person to identify rare or highly significant specimens. Follow the appropriate regulations when dealing with endangered species.
• Use of historical building fabric: recreation of a period setting can pose ethical questions.

For example, it may be inappropriate to remove selected architectural features from an historic building that may be restored or preserved.

• Recreation of settings that are sacred to a culture: a religious ceremony may be an inappropriate subject to depict. The incorporation of human models in an exhibit may also be considered problematic by some members of a culture.