Properties of wood
Wood forms a special relationship with those who interact with it due to a unique “warmth” not found in by competing materials such as metals or stone. In its raw and natural form, wood is organic and non-living, yet still dynamic in its characteristics that change with various environmental variables (e.g. temperature and humidity).
Depending on the way wood is cut and processed, additional qualities are modified and accentuated (or diminished) to suits its intended use. These are some of the most common and familiar characteristics that we experience on a daily basis.
Sensory characteristics
Colour, lustre, odour, taste, texture, grain, figure, weight, and hardness of wood. These properties are most easily discernable by the senses that we receive and process on a daily basis.
Density and specific gravity
The density of wood is subject to environmental conditions because of its ability to absorb moisture from the air. Some wood is so dense that it will sink in water, while others will easily float on the surface.
Mechanical properties
The mechanical properties, or the strength of wood are measures of its ability to resist applied forces that can change its shape and size. Wood has significantly different strength properties parallel to the grain than it does across the grain, and its strength is also affected by other factors such as moisture content and density. The science of why wood moves.
Thermal properties
Wood expands and contracts with changes to the temperature, but these are relatively minor compared with shrinkage and swelling caused by varying moisture content.
Wood has a high heat-insulating capacity compared with materials such as metals, marble, glass, and concrete. Its thermal conductivity is highest in the axial direction, increasing with higher density and moisture content; light, dry woods therefore make better insulators.
Electrical properties
Oven-dry wood is electrically insulating, however, once its moisture content increases, electric conductivity of saturated wood can approaches that of water.
Acoustic properties
Wood is a unique material for making musical instruments because can produce sound as well as amplify or absorb sound waves from other sources.
The pitch of sound produced depends on the frequency of vibration (affected by the dimensions, density, moisture content, and elasticity). Higher pitches are produced by smaller dimensions, lower moisture content, higher density and elasticity.
Degradation
Wood can last for hundreds or thousands of years, as it preserves well in the absence of degradation due to external factors such as the presence of bacteria, fungi, insects, marine borers, and climatic, mechanical, chemical, and thermal factors. Degradation causes changes in appearance, structure, or chemical composition.
