SCIENTIFIC NAME
Grevillea robusta. Derivation: The genus name is in honor of Charles Francis Greville (1749 to 1809), a British introducer of exotic plants. The specific epithet is Latin meaning robust.

FAMILY
Proteaceae, the protea family.

OTHER NAMES
grevillea, southern silky oak.

DISTRIBUTION
Native to eastern Australia, silky oak's ability to withstand drought has made it a widely planted cultivar in warm, dry regions, including the southwestern United States. Because its fern-like foliage represses sunlight, it is used to protect sun-sensitive commercial crops such as tea and coffee.

THE TREE
Silky oak reaches a height of 80 to 100 feet with a diameter of 2 to 3 feet. On ideal sites, specimens can reach 150 feet in height with diameters in excess of 4 feet. By Australian standards, it is not a particularly large tree and is displaced on more favorable growing sites by numerous species of eucalypts.

THE TIMBER
Silky oak is a moderately coarse-textured, diffuse-porous wood. The transition between the light-colored pinkish-yellow sapwood and the darker, pinkish buff-brown heartwood is not sharply demarcated. The most striking feature is the woven pattern of its figure resulting from its large and plentiful rays. While these conspicuous rays may explain the use of oak in its common name, silky oak is not closely related to the true oaks (Quercus) which belong to the beech family (Fagaceae). With an average reported specific gravity of 0.51 (ovendry weight/green volume), equivalent to an air-dried weight of 39 pcf, it is much softer than most of the true oaks. Because its ray tissue has extremely high luster in comparison to the rather dull background tissue, carefully sliced radial veneer reflects light to make this one of the showiest inlay woods in the world. Silky oak compares closely to bigleaf mahogany (Swietenia macrophylla WDS 254) in terms of most strength properties. It is much weaker than virtually all of the true oaks, but is strong enough for use in fine furniture.

SEASONING
While silky oak has moderately low volumetric shrinkage, the relatively high contrast between its tangential shrinkage of 7.7% (green to ovendry) and its radial shrinkage of only 2.7% suggests a potential for considerable drying stress. Honeycomb and collapse sometimes occur, especially when thicker stock is exposed to harsh, overly accelerated, kiln schedules.

DURABILITY
The heartwood is moderately durable, but this is not an outstanding wood for exterior marine applications.

WORKABILITY
Due to its dominant rays, silky oak tends to chip when planed. Its moderately low density makes it somewhat more pleasant to work than most of the true oaks. For such a highly figured wood, it turns well. Most highly figured woods tend to be ring porous and these open-grained woods often do not perform well on the lathe. Silky oak, on the other hand, achieves its flamboyant figure by virtue of its unusually vivid rays, but otherwise has the working qualities of a diffuse-porous wood. It steam bends well, accepts virtually all glues and finishes and will accommodate large diameter fasteners without splitting. A major drawback is that it contains some toxic, phenolic compounds that can cause serious skin rash. As with poison ivy, not everyone is susceptible, but if exposure causes itchiness, leave it alone.

USES
Uses include furniture, inlay and plywood veneer, turnery and decorative but not durable parquet flooring.

SUPPLIES
Although silky oak is not rare in Australia, the costs of transportation and maximizing its figure make it rather pricey on the American market.

SPECIAL NOTE
In some references, especially those of British origin, Cardwellia sublimis (WDS 060) is defined as lacewood or silky oak. This less drought resistant and more northerly species is native to the coastal rain forests of Queensland and is a closely related member of the Proteaceae family.

Information from A Guide to Useful Woods of the World, Second Edition, James H. Flynn, Jr. and Charles D. Holder, Editors. Forest Products Society, Madison, Wisconsin, 2001.

Photographs from MDArtworks