There are many species in the Eucalyptus genus. Some are small and produce leaves for floral arrangements. Others (including jarrah, blue gum, karri and Tasmanian oak) produce excellent timber and lumber products. Jarrah (Eucalyptus marginata) is a dark red wood with outstanding strength and stiffness. This species is found along the coastal area of southwestern Australia, but is imported into the United States, primarily into West Coast ports.
The tree itself can be quite large - up to 150 feet tall and 5 feet in diameter - which means a lot of clear lumber. In fact, this species is one of the most important timber species in Australia. It has natural decay resistance and fire-resistant properties.
If you need a beautiful red hard floor or are making furniture for outdoor use, this is the premium species. Because of its natural color, the wood can be just waxed for a durable finish.
Processing suggestions and characteristics
Density. The specific gravity of green lumber is 0.68. The basic lumber weight, when dried to 6 percent MC, is 51 pounds per cubic foot, or more than 4 pounds per board foot. This is nearly 20 percent heavier than red oak, which weighs 43 pounds per cubic foot.
Drying. This wood dries slowly, often with considerable risk of warp. Generally, the wood is dried similarly to American oak. Supplies sent to North America would always be dried before being exported.
Gluing and machining. Unless tools are very sharp, this is a difficult species to machine, due to its high density. Interlocked grain also means that machining equipment must be in perfect operating order.
Gluing is moderately difficult, as with most dense species. Gluing soon after machining the mating surfaces is essential, as is common with dense woods to avoid moisture changes and nonflat surfaces.
Stability. Tangential shrinkage (the width in flatsawn lumber) is high, about 9 percent; radial, 6 percent.
Movement in service is moderately high, especially when compared to native U.S. species. A 1 percent size change tangentially can occur with 2.6 percent MC change; radially, with a 4 percent MC change. Correct final MC is essential to avoid in-use size changes.
Strength. Due to its high density, jarrah's strength and stiffness are exceptionally high. For dry wood, the ultimate strength (MOR) is 16,200 psi, stiffness (MOE) is 1.88 million psi and hardness is 1,910 pounds. Comparative oak values are 14,300 psi, 1.82 million psi and 1,290 pounds. The high hardness makes it a good choice for flooring, especially industrial flooring, and other high-impact, high-strength areas. High natural decay resistance makes this a good choice for boardwalks and exterior flooring, as well as outdoor furniture. Bending stock is another good application.
Nails and screws have excellent holding power, but predrilling of holes is necessary in most cases.
Color and grain. Heartwood is dark red brown, darkening somewhat with exposure. Gum pockets are occasionally found. The surface texture is somewhat coarse with many small open pores. Surfaces would not be considered exceptionally smooth. The grain is usually quite straight, although sometimes there may be some interlocked grain.
The tree itself can be quite large - up to 150 feet tall and 5 feet in diameter - which means a lot of clear lumber. In fact, this species is one of the most important timber species in Australia. It has natural decay resistance and fire-resistant properties.
If you need a beautiful red hard floor or are making furniture for outdoor use, this is the premium species. Because of its natural color, the wood can be just waxed for a durable finish.
Processing suggestions and characteristics
Density. The specific gravity of green lumber is 0.68. The basic lumber weight, when dried to 6 percent MC, is 51 pounds per cubic foot, or more than 4 pounds per board foot. This is nearly 20 percent heavier than red oak, which weighs 43 pounds per cubic foot.
Drying. This wood dries slowly, often with considerable risk of warp. Generally, the wood is dried similarly to American oak. Supplies sent to North America would always be dried before being exported.
Gluing and machining. Unless tools are very sharp, this is a difficult species to machine, due to its high density. Interlocked grain also means that machining equipment must be in perfect operating order.
Gluing is moderately difficult, as with most dense species. Gluing soon after machining the mating surfaces is essential, as is common with dense woods to avoid moisture changes and nonflat surfaces.
Stability. Tangential shrinkage (the width in flatsawn lumber) is high, about 9 percent; radial, 6 percent.
Movement in service is moderately high, especially when compared to native U.S. species. A 1 percent size change tangentially can occur with 2.6 percent MC change; radially, with a 4 percent MC change. Correct final MC is essential to avoid in-use size changes.
Strength. Due to its high density, jarrah's strength and stiffness are exceptionally high. For dry wood, the ultimate strength (MOR) is 16,200 psi, stiffness (MOE) is 1.88 million psi and hardness is 1,910 pounds. Comparative oak values are 14,300 psi, 1.82 million psi and 1,290 pounds. The high hardness makes it a good choice for flooring, especially industrial flooring, and other high-impact, high-strength areas. High natural decay resistance makes this a good choice for boardwalks and exterior flooring, as well as outdoor furniture. Bending stock is another good application.
Nails and screws have excellent holding power, but predrilling of holes is necessary in most cases.
Color and grain. Heartwood is dark red brown, darkening somewhat with exposure. Gum pockets are occasionally found. The surface texture is somewhat coarse with many small open pores. Surfaces would not be considered exceptionally smooth. The grain is usually quite straight, although sometimes there may be some interlocked grain.
