Sapele (pronounced sa-pee’-lee) is in the African mahogany family. Indeed, sapele (Entandrophragma cylindricum) has the appearance of African mahogany; that is, sapele is dark reddish brown with a ribbon pattern. It is actually heavier, stronger and harder than African mahogany. Its excellent working properties and wonderful appearance result in a moderate to high price in the lumber market. This wood is also available as veneer.
The tree grows in the tropical rain forests of Africa, ranging from the Ivory Coast to Cameroon and eastward through Zaire to Uganda. On the edge of its range, it has been harvested heavily and may be nearing extinction; however, in most of its range it is more plentiful and can be grown in plantations, assuring good supplies into the future with good forestry practices.
The tree in the natural forest will reach a height ranging from 100 to 150 feet, with some trees reaching 200 feet in height. Tree diameters can reach 6 feet, although 4 to 5 feet are more common. The merchantable stem is typically straight, free of branches and over 100 feet long. As might be imagined, this large tree produces tremendous volumes of clear lumber and veneer.
As the tree is growing, the vertical cells do not align vertically in the tree, but are aligned at a small angle. In other words, the grain spirals up the tree, similar to the stripes of a candy-cane. The direction of rotation also reverses from year to year. This phenomena is called, when the wood is sawn into lumber, interlocked grain. When quartersawn or riftsawn, this interlocked grain creates a wonderful (and desirable) ribbon pattern on the face of the lumber.
As with many imported species, this wood is subject to attack by powderpost beetles which are common in tropical regions. They can be eliminated by fumigation when shipping or kiln drying above 133 degrees F. Once treated, the “sterilized” wood must be kept away from unsterilized, infected wood.
Processing Suggestions and Characteristics
Sapele is similar in density to red oak, but heavier than mahogany. Kiln-dried wood has a density of 36 pounds per cubic foot. Lumber planed to ¾ inch thickness 7 percent MC will weigh about 2-1/4 pounds per board foot.
Drying and Stability
Sapele may be dried at the sawmill, but it is not uncommon to bring the wet wood to the U.S. for drying. It dries rapidly, but the interlocked grain results in a strong tendency to warp. This warp is best controlled by excellent stacking and low initial temperatures. Kiln schedules are similar to red oak.
Overall shrinkage in drying (about 5-1/2 percent in width of flatsawn lumber and 3-1/2 percent for quartersawn) is not excessive.
This wood moves somewhat in service when the humidity changes. Quartersawn lumber that shows the ribbon stripe will actually be fairly stable in width, requiring a 6 percent MC change to produce a 1 percent size change. Flatsawn lumber will move 1 percent with a 4 percent MC change.
Gluing and Machining
Gluing is moderately easy, but with the high density of the wood surfaces should be flat and freshly prepared. There are no resins to deal with.
The interlocked grain means that on quartersawn and rift surfaces, the tool is always cutting some of the fibers “against the grain.” Tear-out (torn grain, chip-out) is therefore likely, especially for low MCs and slender knives. The hook angle should be small so that the knife acts more like a plow than like a splitting chisel.
Sapele is a little stronger than red oak. The bending strength (MOR) is 15,300 psi, the elasticity (MOE) is 1.82 million psi, and the hardness is 1510 pounds.
Screw and nail holding is very high; predrilling of screw and nail holes near the ends of the pieces is be suggested to avoid splitting.
Color and Grain
Sapele is almost always 100 percent heartwood. The heartwood is dark reddish brown with a purplish cast. The grain texture rather fine, similar to mahogany. The interlocked grain on quartersawn surfaces produces the ribbon like pattern. There is a very slight aroma at times which smells a bit like cedar.
When sanded smooth, the wood has a slight luster. It may be necessary to use a sealer on the wood surfaces (or use multiple coats), as there can be variations in absorption of the finishes without a sealer.