Wood: Materials for Furniture 1

Wood: Materials for Furniture 1. Style and Design The style, or general appearance of furniture during a The furniture industry has relied heavily on wood and period of time, changes over the course of history. wood-based materials throughout history. Furniture Style reflects the priorities of the culture at the time. has evolved from simple utilitarian objects made to The furniture of early civilizations reflected the desire support people and inanimate objects to articles that of the privileged and ruling classes to display their are designed and built with both functional and power, wealth, or zealous aspirations. From the aesthetic characteristics and intended for display as beginning, furniture style was influenced by archi- well as utility. The origin and development of furniture tectural style. Ample evidence exists indicating that can be traced to an innate human desire to provide for Egyptian architectural ornamentation was applied to comfort and convenience as well as to display wealth, ancient Egyptian furniture and changes in Greek social and political status, or power. Furniture is made architecture were reflected in Greek furniture styles. from many materials, from rattan to precious metals, Beginning in the late nineteenth century, architects but from the earliest recorded history to the present, began having a direct influence in the design of the dominant material chosen for constructing fur- furniture, attributable to their desire to furnish niture is wood (see Wood: History of Use). Wood buildings in harmony with the overall design of a furniture was present in the ancient cultures of China, structure. The common element among all of these Egypt, and Greece. Historic research indicates that styles is the use of wood. early Egyptian furniture was constructed from the The elements of design incorporate both style and indigenous woods of acacia, almond, fig, palm, tama- structural integrity. Design has evolved from the risk, willow, and poplar and also from exotic woods of subjective trial-and-error approach of the artist to one ebony, cedar, ash, beech, oak, yew, elm, and cypress. of using engineering principles to choose materials and Although much of this early furniture has not sur- design elements based on the mechanical properties of vived, the dry climate of the Egyptian pyramids has the materials (Eckelman 1978). Although engineering provided numerous examples of ancient wooden design of furniture is practiced in many modern furniture (Morley 1999, pp. 14–16). furniture-manufacturing facilities, much of the world’s The reasons for selecting wood as a preferred furniture is still designed and built the intuitive way material for furniture are much the same now as they and by full-scale testing of prototypes. There is were thousands of years ago. Wood excels in per- growing interest in developing better analytical formance, manufacturing, and appearance charac- methods to help the furniture designer optimize the teristics. From the consumer’s point of view, wood has production of a cost efficient and safe product a pleasing appearance, is warm to the touch, and is (Smardzewski 1998). strong and durable. From a manufacturer’s point of The desire to create different or new appearances in view, wood has many positive attributes: a favorable furniture style led to the use of different manufacturing strength-to-weight ratio; easily worked with a wide methods and materials. Examples of methods and variety of tools to make artistic and functional shapes; materials include the invention of veneering and inlay, easier to join to other pieces of wood or other materials frame and panel construction, bending techniques, than most other structural materials; can be readily and the use of plywood and composite materials. finished with varnishes, paints, and similar materials Although ancient Egyptians invented many of these to enhance or modify its natural appearance; common techniques, they needed to be modified and improved and available near population and manufacturing to be compatible with the economic and technical centers; and a renewable resource. demands of the industrial age. In the modern style, Wood continues to be the overwhelming choice of nonwood materials such as metals and plastics were customers, who often identify the most important often chosen by designers to achieve the desired look. attributes to be reliability, environment friendliness, Although these nonwood materials have made sig- pleasing appearance, and good value (Pakarinen nificant inroads into furniture manufacturing, the bulk 1999). Evidence suggests that the wood industry has of the furniture made today is still made from wood or an opportunity to capture the environmentally in- wood-based materials. In the USA, pine (Pinus spp.), formed consumer by providing certified wood that is maple (Acer spp.), and cherry (Prunus spp.) were the produced according to accepted standards of environ- preferred furniture materials through the nineteenth mentally sustainable management; the customer’s century, giving way to a strong preference for oak perception of environmental impacts is beginning to (Quercus spp.) fueled by the styles of the late nine- influence the manufacturer’s choice of materials teenth-century arts and crafts movement. Oak remains (Stevens et al. 1998). the species most used for furniture in the USA. 1 Wood: Materials for Furniture 2. Material Properties Decay During Use). This property is not an important consideration for interior-use furniture. It is, however, The elements important in the selection of materials an important performance criterion for outdoor-use for furniture manufacturing can be defined by the furniture. Species with a high degree of durability such material properties. The fundamental wood charac- as redwood, cedar, and teak are ideal choices for teristics of anatomical structure and density are highly outdoor furniture because of their high degree of correlated to the physical and mechanical properties durability. that affect performance, manufacturing, and appearance characteristics important for furniture materials. Wood continues to be a favorite furniture material because it excels in most of the manufacturer’s and 2.2 Appearance Characteristics consumer’s selection criteria described above as desirable attributes, and it is readily available and The appearance is often of primary importance when cost-competitive with other possible materials. choosing furniture woods for items where the wood surface is readily visible. The appearance characteristics are not important for the secondary woods (those not visible) used in solid wood or upholstered 2.1 Performance Characteristics furniture. For furniture that has exposed wood, the color, texture, and figure (grain pattern) of the wood How well a particular wood performs in any product determine the aesthetic quality of the item (see Wood: is in large part a function of the wood density (see Macroscopic Anatomy). Color is determined by the Wood: Density). Density is a good predictor for chemical composition of the extractive component of strength and stiffness, two mechanical properties that wood. Texture is directly related to the structure and are very important considerations for furniture (see distribution of anatomical features such as wood rays, Wood: Strength and Stiffness). Because all furniture is annual rings, and hardwood vessels. Figure is a designed to carry a load, it is necessary to choose wood reflection of the orientation of these anatomical that has the necessary strength and stiffness to perform features to the aspect of the wood surface. In general, the intended task, be it to support a person or a hardwoods have more desirable color, texture, and heavy load of books. Wood in the density range V figure than softwoods because of the more complex 400–800kgm $ (oven dry mass, green volume basis) is anatomical structure found in hardwoods. The highest preferred (Webster et al. 1984). Lower density woods value furniture woods, such as rosewood and walnut, have inferior strength and stiffness properties and are often those with unusual and striking figure and\or manufacturing characteristics. Higher density woods color. are often undesirable because they are more costly to process and they may yield a piece of furniture heavier than desired by the customer. Dimensional stability, or the ability to maintain a 2.3 Manufacturing Characteristics desired dimension during normal exposure to fluc- tuations in relative humidity, is a very important Important considerations in choosing furniture woods performance consideration in furniture design and are the machining, joining, and finishing charac- construction (see Wood: Dimensional Change from teristics of the wood. Density also has a significant Moisture). Density is highly correlated with dimen- impact on these characteristics. Low-density woods sional stability. Therefore, high-density woods are often exhibit poor machining and finishing qualities. generally less dimensionally stable than low-density High-density woods cause increased wear of cutting woods. However, if the wood is properly dried to its tools. Also, since density is a measure of the amount of target moisture content, dimensional stability is usual- cell wall substance in a given volume of wood, it is ly adequate for most furniture uses. Difficulty is highly correlated to permeability. Permeability has a encountered when furniture is exposed to warm, slight effect on gluing and finishing characteristics but humid climates. In this situation it is wise

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