Furniture and wooden objects are part of our lives every day. Some are utilitarian, such as a chair at the dining table; others are aesthetic, such as an antique sculpture or carving; still others may have an emotional or symbolic importance as mementos, such as a chest that has been in the family for years.
Whatever their nature or purpose, if they are important to us they deserve the best care we can provide for them – unlike the chair illustrated on the cover of the video case, which is being gently misused. The information in this booklet is not about restoring or repairing furniture and wooden objects; it is about caring for and preventing damage to them. Understanding and dealing with the causes of damage are well within the abilities of nearly all caretakers of valued wooden objects, whether a collections manager at a major museum or an individual safeguarding family heirlooms. The aim of this booklet is to explain how to minimize the preventable damage to furniture. Preventable Damage Damage to and destruction of furniture takes many forms and paths. We use the term “preventable damage” to describe those conditions and events over which a furniture caretaker has some influence. By far the most predominant damage to furniture is caused by poor choices its users and caretakers make through misunderstanding the nature of wooden objects. Consider the major causes of preventable damage: • Poorly controlled ambient environment (light, relative humidity and temperature) • Careless use, handling, and maintenance • Inadequate packing for transport or shipping This booklet and the accompanying video discuss the first two of these three causes of preventable damage. (A subsequent booklet and video, Furniture Packing and Transport, will deal with the practical aspects of packing.) While all things degrade, the process can be slowed through application of principles of care and maintenance based on understanding the nature of wood and artifacts made of wood. The Environment In this context “environment” means the conditions under which the artifact exists. In all cases, the “best” environment for furniture depends on the caretaker’s priorities and resources and is often a balancing act between them. There is never a “perfect” environment for anything, only conditions that contribute more or less to the deterioration or preservation of the artifact. As with most materials, however, there is an “optimal” environment that provides the best balance. For furniture and wooden artifacts the “optimal” environment is about 40º Fahrenheit with roughly 50% relative humidity; the “optimal” environment is also dark, anaerobic (an absence of oxygen), and free from contact with anything (or anyone). Keeping furniture in a chamber under these conditions, even if technically and financially feasible, makes it pretty difficult to use. 
So we must at least try to understand the effects of light, varying temperature and humidity, and potential for damage from use in order to make the choices that best fit our desires for using or preserving furniture. Light Probably the easiest environmental issue to understand and resolve for furniture is damage from light. What we normally call “light” is really just a very narrow portion of the phenomenon called “electromagnetic radiation” that corresponds to the sensitivity of our eyes. Simply put, light is a source of energy. Light interacts with everything it illuminates, and light energy is directly translatable to damage to furniture surfaces. The amount of that damage depends on the intensity and color. Bright light is more damaging than dim light, blue light is more damaging than red light. For the most part, light damage takes the form of discoloration, usually bleaching. Light induces bleaching and degradation in most components of furniture: coatings, whether transparent or polychrome; the wood itself; and especially upholstery textiles. Generally, light damage is cumulative and permanent. Responding to the potential for light damage is relatively simple and can also be straightforward: when the furniture is not in use, it is best left in the dark. Even when furniture is in use and in the light, damage can be reduced through common devices like window shades, curtains, and screens for protection from direct sunlight or elevated light levels. Ultraviolet filter films can be used to block the most damaging light frequencies if there is concern over the color of the light, for example light from fluorescent bulbs or ultraviolet radiation from sunlight. For extended periods of non-use, opaque dust covers are recommended. The most important thing to keep in mind is the relationship between light and damage to furniture surfaces. As long as there is light, there will be light damage proportional to its intensity and exposure time. But the application of simple measures can go a long way to reducing damage. Relative Humidity Perhaps the greatest environmental damage to furniture comes from wide swings in relative humidity (RH). Wood absorbs and desorbs water as relative humidity rises and falls, and in doing so it swells and shrinks. Making matters worse, it expands and contracts unequally along different grain directions. This characteristic remains as long as wood exists, whether it is new from the lumberyard or thousands of years old from an ancient tomb. As humidity changes, the components of wooden objects are continually pushing and pulling against each other. This pressure often results in parts of furniture no longer fitting together closely or becoming distorted or breaking from their own internal stresses. Wood is not the only furniture component to suffer from humidity swings. As they age and deteriorate, coatings become more inflexible. Since the wood continues to move with humidity changes, and the coating becomes increasingly brittle with time, humidity fluctuations eventually cause the coatings to begin fracturing or separating from the substrate.
This problem becomes particularly severe when coatings are likely to be less flexible from the start, such as painted surfaces or gilding, which is often applied over a rigid ground called gesso. The response to relative humidity changes begins with determining the annual average RH for your particular climate. Then try to keep the RH in the space where your furniture is a close to that average as possible, generally within about 10% up or down. This stability can be achieved through de-humidifying in the summer and humidifying in the winter. Be aware that raising the temperature lowers the humidity and vice versa. Thus, modern heating systems, which can drive down interior RH in the winter, almost invariably cause problems for furniture. To counteract their effect, you can modify the RH by keeping furniture-containing spaces cooler in the wintertime. A humidistat automatically adjusts temperature to maintain a stable relative humidity. Biopredation The third, and most often overlooked environmental problem is biopredation. Wood is subject to attack by both animals and micro-organisms, including insects, rodents, and fungi. The best protection against biopredation is to monitor your furniture regularly and keep food separate from your furniture, or at least stored in sealed containers. Insect infestation Insect infestation, in particular, can destroy a furniture collection in a short time. Termites, carpenter bees and ants, powder post beetle larvae, and other insects can severely damage wood by eating channels beneath the surface. The larvae tunnel through the wood until they are ready to emerge through exit holes at the appropriate time in their life cycle. At these exit holes the chewed and digested wood is often pushed out as the insect exits. These are important clues for you in monitoring furniture, as the sides of recent exit holes have the color of newly-cut wood. Piles of insect excrement and wood dust, called fras (or frass), under or on your furniture may indicate an active infestation. Quarantine the suspect object immediately. If the infestation is confirmed, fumigation will be necessary. In addition, you will need to increase monitoring of objects near the affected furniture, for likelihood of their being infested is now greatly increased. Rodents Rodents usually do not eat the wood for its own sake but rather gnaw through it to get to the food on the other side. The best way to prevent rodent damage is to not store any food, including condiments, in wooden furniture. Since food also attracts insects, it is a good idea to keep food as far from your collection as possible. 
The presence of rodents in a piece of furniture are more symptomatic of problems with the building envelope, which must be sealed to keep rodents out. Mold, Mildew and Fungi Mold, mildew and fungi are everywhere – on furnishings, walls, and in the air. But fungal infestation will occur only in the presence of an external moisture source or when the fiber saturation point (nearly 100% RH) is approached. Still air and high temperatures also encourage the rapid growth of these organisms. Molds and mildew growing on the surface of wood may stain it. Other fungi can completely destroy wood. The control of mold and mildew is quite simple: do not let the relative humidity rise above 70%. Even if an active infestation exists, lowering the RH will cause the mold and mildew spores to become dormant. Similarly, cooler temperatures will also reduce fungi growth. Lowering the RH in a damp area should be done very slowly to prevent excessive stress and possible warping and splitting of wooden furniture. Once the room is allowed to dry out to a humidity level below 70%, the dried, inactive mold residues can then be carefully vacuumed off furniture surfaces. Be careful not to breathe or scatter the dust, and clean the vacuum after use. It is also important to locate any source of excess moisture and determine what can be done to remove it. Underground walls should be sealed and vapor-proofed. Leaks should be repaired in roofs and walls. Fungal damage, or rot, can only occur in areas of extreme dampness at moderate temperatures. Unless your furniture gets wet and stays wet, this type of damage is not normally a severe problem. However, if your furniture is stored in areas where water incursion is a common problem, such as basements or attics, these areas must be surveyed every time it rains or snows. Furniture Use and Care Careless and uninformed treatment of furniture is the second major cause of preventable damage. Damage to furniture is telltale: it is either caused by poor construction (over which the caretaker has no control) or it is the result of improper use or care. You don’t have to be a specialist or scholar to treat furniture properly, all it takes is a basic understanding of the nature of wooden objects and of what furniture is and is meant to do, combined with common sense. Here are some common-sense pointers: • Protect surfaces from fire and excessive heat • Sit only on structures designed for that purpose • Be careful about what you place on a piece of furniture Hot items, such as irons, coffee mugs, and steaming tureens can literally melt a finish away. Water from spills and condensation from vases and cold drink glasses can damage and deface coatings through “blooming,” an effect that makes transparent coatings white or milky. Damage is even worse when the liquid itself stains the surface, such as when ink or coffee or tea is spilled, or if the coating is penetrated and the staining liquid enters the wood itself. Organic solvents, such as fingernail polish and remover, perfumes, and alcoholic drinks can behave as paint and varnish removers on many kinds of coatings. These problems are simple to address. Using coasters, oversized ashtrays, and writing pads can virtually eliminate the potential for damage. Handling and Moving Furniture In addition to using furniture wisely, it is important to handle it carefully. Safe handling and moving of furniture begin with a basic understanding of how a piece is constructed. The second step is to plan carefully. General Concerns Before picking up a piece of furniture, determine how it is put together and if any of its parts are removable or detachable. Make sure you know where the furniture is its strongest – generally along a major horizontal element – and try to carry it from these points. Then examine the room and the route whereby the furniture is to be moved. Look around to make sure you know where everything is. Identify potential trouble. Light fixtures that hang low, for examples, or that extend out from the wall may be damaged or cause damage. Glass table tops are also easily damaged if bumped. If necessary, clear the way by moving or removing fragile or obstructive items. Protect the furniture to be moved with soft padding or wrap it in a blanket pad. Padding, which will provide extra insurance against bumping and gouging, is especially important if an item is going into storage. Before moving an item, make sure you know exactly where it goes next.
Plan ahead to adjust the temperature and relative humidity in the new location so they are the same as where the furniture presently is. Extreme changes in temperature and humidity can cause splitting of joints and veneers. Never hurry when you are moving furniture. Scratches, dents, and gouges from bumps against hand truck, doorways, and other furniture are always more likely in haste. Each item needs to be approached individually, without haste, and with sufficient manpower present. Make sure you have a firm grip on the piece with both hands. Do not wear cotton gloves. It is essential that hands not slip from a piece of furniture while it is being moved. Never slide or drag furniture along the floor. The vibration can loosen or break joints, chip feet, break legs, etc., to say nothing of what dragging does to the carpeting or finish on the floor. Whenever possible, use trolleys or dollies for transporting heavy pieces. Handling valuable furnishings requires a special attitude: in general, movement should be carried out at a slower pace. Here are some quick tips for moving furniture properly. Remember: If you don’t break it, it doesn’t have to be fixed! • Just as gymnasts work with “spotters” to catch them when they misstep, have helpers on hand to guide the movers so they don’t crash into walls or other pieces of furniture • Anticipate trouble; think through every step; plan ahead; and do everything with care • Make sure the route is clear and has no obstructions, such as narrow doorways or hanging chandeliers that might hinder the safe passage of furniture and movers
