Common Names:   Koa Purchase Koa

Mechanical Values

Environmental Profile
Although the environmental profile of Koa has not been officially assessed, it is generally believed to be rare within its natural habitat. 

Distribution
Koa trees are reported to be found exclusively on the Hawaiian Islands. They grow in moist soils from sea level to the top of volcanic mountains, and are reported to be quite adaptable to a wide variety of climates.

Product Sources
Some material from this species is reported to be available from environmentally responsible sources. 

Supplies of Koa are reported to be available on the U.S. market in the form of lumber and veneers. Prices are reported to be in the high range.

Tree Data
The trees are reported to be very hardy and can survive under almost any environmental condition. Under optimum growing conditions the trees are reported to reach 80 to 100 feet (24 to 30 m) in height, with trunk diameters of 36 to 48 inches (90 to 120 cm).

Sapwood Color
The sapwood is pale brown in color, and is clearly demarcated from the heartwood. 

Heartwood Color
The distinct heartwood varies in color from tree to tree. It ranges from pale blond or golden brown to a deep chocolate color, but the most common color is reported to be reddish brown. The wood yellows quickly in sunlight, which adversely affects its exterior performance.

Grain
The wavy and curly grain is moderate to severely interlocked. The wood usually has light and dark bands in the growth rings. The grain produces various attractive patterns, such as fiddleback and rainbow.

Texture
The texture is moderately coarse.

Luster
Wood surface is described as highly lustrous.

Odor
There is no distinct odor or taste.

Ease of Drying
Lumber and veneer are reported to dry easily with little or no degrade.

Drying Defects
Some surface checking may occur in thicker samples. Stock of normal thickness usually dries without any problems.

Kiln Schedules
T6 - D4 (4/4); T3 - D3 (8/4) US
Schedule F (4/4) United Kingdom

Movement in Service
Seasoned wood is reported to be stable, and retains its shape well in use.

Natural Durability
The wood is not resistant to decay and is reported to be highly susceptible to attack by the subterranean and dry wood termites.

Resistance to Impregnation
The wood is very resistant to impregnation.

Cutting Resistance
The wood is reported to be rather difficult to saw because of interlocked grain. Tools should be kept sharp to prevent tearouts.

Blunting Effect
The wood has medium blunting effect on tools.

Planing
The timber is reported to be fairly easy to work, and responds fairly readily to both hand and machine tools in planing, turning, boring, and almost all woodworking operations. End-grain material is reported to require very sharp cutting edges. Wood containing curly grain may require a cutting angle of 20 degrees for best results.

Gluing
Gluing properties are reported to be variable, but they are generally poor.

Nailing
The timber is reported to take nails well.

Screwing
The wood has good screwing properties.

Polishing
The wood can take a high polish. 

Staining
The timber is reported to stain very well.

Varnishing
The wood takes varnish very well.

Strength Properties
Bending strength in the air-dry condition (about 12 percent moisture content) is fairly high. Strength in compression parallel to grain is also fairly high. Weight and density are high. 

Comments
The wood is popular for the manufacture of musical instruments because of its high resonant properties. Hawaiian ukeleles are reported to be made exclusively from koa wood. Trees that grow at high, exposed areas are reported to produce the best figured wood, and the veneer form of Koa is highly valued for fine furniture because of its fiddleback figure and high finish it takes. Koa wood is reported to be comparable to that of Black walnut (Juglans nigra ).