Wood Products
Sawnwood (hardwood & softwood)
Timber is a natural product drawn from the wood in tree trunks. It is a renewable material that is both beautiful and durable and can be used in a broad range of design applications.
Photo: NSW Department of
PrimaryIndustries
Timber is light and versatile and can be used in both interior and exterior structures and surfaces. It can be used in its original shape, rough sawn, or hewn (cut) to size. It can be dressed to a smooth finish, machined into a variety of shapes, or sliced into sheets of veneer.
The character of timber is consistent with the species of tree and its form and growth over time. Timber properties such as strength, hardness, durability and appearance all vary between different species.
Commercial timbers are usually classified into two main groups – hardwoods and softwoods. Hardwoods are those woods from flowering trees bearing covered seeds, such as eucalypts and oaks. The botanical name for hardwood species is Angiosperms. Softwoods produce uncovered seeds, usually in cone-like structures. Softwoods include pines and other conifers, and are known botanically as Gymnosperms. The terms softwood and hardwood do not indicate the softness or hardness in particular timbers. In some instances, hardwoods are actually softer and lighter than softwoods.
Photo: Forest Wood Products Research
& Development Corporation
Hardwood and softwood is sold as sawn wood cut from logs and dried. It is preferable that the logs come from straight, upright trees, as leaning trees are susceptible to compression in softwoods and tension in hardwoods. This can lead to lower timber quality and losses of useable timber during sawing and drying.
The timber is graded according to the Australian Grading Standards. Appearance grading involves the sorting of timber into groups with similar characteristics and properties. For example, timber that is uniform in appearance with few natural features may be classified as select grade, while timber classified as high feature grade will have many natural features, giving it a natural aesthetic.
Although appearance is important, features such as diameter of log, age, straightness, length, and number of defects or growth stresses are also important. All of these can influence processing costs and the recovery of particular products. A log that best meets market specifications will be worth much more than a poor log, and this is reflected in market price.
The volume of sawnwood production in Australia has increased by more than 30% over the last ten years. This increased production has replaced imports, positively impacting on economic activity in the industry.
Case Study: Maintaining furniture function from the tropics to the snowfields
Wood contains moisture, even after seasoning or drying, and constantly tries to equalise with the humidity conditions of the surrounding environment. The subsequent change in timber moisture content causes swelling or shrinkage of wood components. The result is often unacceptable performance, such as opening of joints, ‘jamming’ of drawers and cabinet doors, and failure of glues and surface coatings.
Photo: istock
DPI&F researchers monitored environmental conditions at furniture production plants around Australia, and investigated the environmental changes experienced by consignments of wood products shipped around the globe.
During a shipment of outdoor furniture from Brisbane to Bermuda, via New Jersey, the timber moisture content ranged from a minimum of 6.2 percent to a maximum of 15.6 percent, with a mean of 10.1 percent. The wide range of environmental conditions experienced during the two-month shipping period could cause unacceptable movement of timber components, if they were not designed to accommodate this movement.
The information that was collected provides a guide to the range of conditions that exported wood products might experience during their service life. This data can be linked to timber species stability factors to provide design parameters for designers, engineers, and manufacturers, and ensure optimum performance under a wide range of conditions, anywhere in the world
