Storage and Display
The environment can have a profound effect on the preservation of furniture. Light, particularly visible and ultraviolet (UV) light, is very damaging to organic materials such as wood, and damage from light is cumulative and irreversible. Clear finishes often turn yellow or opaque in response to light, and the color or cellular structure of the wood itself can also change. The resulting damaged finishes and bleached wood cannot be restored to their original color without stripping and refinishing, a practice not recommended as loss of the “patina,” or evidence of use, can negatively affect the furniture’s monetary value.
To limit the effects of light, move all furniture out of direct sunlight, and utilize blinds or curtains to block the light’s intensity. UV light, which is particularly damaging to wood and fabrics, can be screened out by applying a UV-filtering film to windows.
Furniture can also be affected by the amount of moisture in the air. Wood and other organic materials respond to changes in relative humidity (RH) by expanding or contracting as they try to maintain equilibrium with the moisture in the environment. Ideally, RH levels should be maintained within a 40 and 60 percent range. If the RH is too high (above 70 percent), wood and other materials expand. If they are constrained in any way, they may split upon shrinking when the RH drops to a lower level. Changes in RH can even cause a coating to detach. A prolonged high humidity environment will also promote the possibility of mold growth and insect infestation. To prevent damage, place furniture in areas of minimum temperature and RH extremes. Avoid storing furniture in attics and basements or placing pieces near fireplaces and heating vents.
Monitoring temperature and RH in an environment can be done with thermometers and hygrometers purchased at electronic or hardware stores and the RH can be modified to stay within acceptable ranges through the use of humidifiers and dehumidifiers.
A common furniture pest is the powderpost beetle, less than a quarter-inch long, which lays its eggs in small crevices. The insect larvae burrow into the wood, creating networks of tunnels as they eat their way along the grain. As they mature to adults, they bore out of the wood leaving an “exit” or “flight” hole and fly off to lay their eggs, completing the cycle.
If flight holes are observed in furniture, it is important to determine if the infestation is active. Active flight holes are light-colored and contain a fine, sawdust-like material called frass. Any material resembling sawdust that appears on the floor underneath a piece of furniture could be a sign of a possible infestation. Frass from an infestation that is no longer active can be dislodged if furniture is moved or jostled, giving an impression of insect activity, but should frass continue to appear after being swept away, it is likely that the infestation is active. If furniture or other wooden objects appear to have active infestation, they should be isolated immediately by placing them in a large sealed plastic bag. As fumigation may be the next step—and there are a variety of methods available to accomplish this end—a conservator, or exterminator familiar with conservation issues, should be called immediately.
Cleaning and Handling
It was once thought that furniture needed to be “fed” with various mixtures of oils and other materials to keep it from drying out. However, a better approach would be to keep furniture in a stable environment. Furniture oils are not recommended for maintenance as many of them contain linseed oil or other drying oils, and when used repeatedly will create a gummy, insoluble surface coating that darkens and obscures the grain of the wood. Other furniture polishes contain non-drying oils such as lemon oil, but attract and entrap dirt and grime. Silicone polishes are also not recommended as they leave a film that is difficult to remove and can interfere with future finish treatments.
The best maintenance for clear-varnished furniture is a coating of good paste wax. Wax is a very stable material that does not change chemically over time and provides protection from moisture and airborne pollutants. Good quality paste wax is available in most hardware stores. A thin coat applied following the directions on the can is all that is needed, no more than once a year. It may not be appropriate to wax furniture that is gilded, painted or lacquered, or furniture that has unstable veneers or flaking finish. Consult a conservator if any question about the appropriateness of waxing arises.
Once a protective coat of wax has been applied, dry dusting with a soft cloth is recommended for routine cleaning. Dust and dirt are harmful to finished surfaces and should be regularly removed as they can scratch or otherwise damage polished surfaces. A soft cotton cloth or artist’s brush is best for dusting. Feather dusters are not recommended for dusting as the feathers tend to get caught in cracks and crevices and can cause detachment of fragile veneers and gilding. A clean cloth slightly dampened in water may help to remove more stubborn dirt. When dusting, be cautious in areas with loose elements such as veneers, moldings, and metal mounts. Should an element become detached, place it in a plastic bag labeled with its original location on the piece until a conservator can reattach it.
If brass hardware on furniture is tarnishing, the owner may want to polish it. In most cases furniture hardware was intended to be brightly polished. There are many brass polishes on the market. Those that contain ammonia can cause long-term corrosion problems, so it is best to choose one of the polishes that has a mild abrasive embedded in cotton wadding. Ideally, hardware should be removed for cleaning so that the polish cannot come into contact with the surrounding wood. If that is not possible or practical, polish the hardware carefully, confining it to the metal only. A good option to a regular regimen of hardware polishing is to have the hardware coated with clear lacquer.
Before moving a piece of furniture, examine it for loose or damaged joinery. If it is safe to move, remove elements such as shelves, doors, and drawers. If doors cannot be removed, secure them by locking or wrapping the case with soft cotton straps. Tables should always be lifted by the apron or legs rather than by the top, which could possibly detach. Chairs should be lifted by the seat rails and not by the arms or crest rail. When moving a large piece, be sure to lift it and not drag it across the floor, as excessive lateral pressure on legs and feet can cause them to shear off. When transporting furniture in a vehicle, place the object on its back or top, not on the legs. If the piece has a marble top, carefully lift it off and transport or store it vertically, as one would a sheet of glass.
Stripping and refinishing furniture is no longer standard practice. An early finish is as important to historic furniture as the legs or any other element. The finish coating offers important data to researchers and is part of the history of the object and once it is removed, it cannot be recovered. It is also desirable to be able to observe on a piece of furniture patterns of wear that indicate the history of use, which stripping and refinishing can obliterate. The appearance of old finishes can often be enhanced without completely removing them by using cleaning materials tailored for specific conditions. The removal and replacement of a surface finish is considered a last ditch effort after other conservation methods have failed. An aged finish, with a patina that only time can produce, can greatly add to the beauty of an object. The primary goal of any treatment should be to maintain the patina of age.
When to Consult a Conservator
The majority of historic furniture is in private hands. Proper care and maintenance is the only way to ensure its preservation for future generations to appreciate. Although some objects may eventually become part of a museum collection, it is nevertheless incumbent on the current owner to provide proper care. Many aspects of furniture care are straightforward and can be carried out by an educated owner. Problems that are beyond an owner’s capabilities should be referred to a conservator.
To search for a conservator near you, go to Find a Conservator >>
The recommendations in this document are intended for guidance only. AIC does not assume responsibility or liability.