USDA Forest Service
Forest Products Laboratory
One Gifford Pinchot Drive
Madison, WI 53705-2398
(608) 231-9200

Wood Technical Fact Sheet

 Cylicodiscus gabunensis

Okan

Family: Leguminosae

Other Common Names: Denya (Ghana), Edum (Gabon), Adoum, Bokoka (Cameroon), Bouemon (Ivory Coast).

Distribution: A large tree 180 to 200 ft in height, bole straight, cylindrical, and clear to 80 ft; trunk diameters about 3 to 4 ft but may reach 8 to 10 ft above short buttresses.

The Tree: Common in the rain forests of Sierra Leone to the Cameroons and Gabon.

The Wood:

General Characteristics: Heartwood yellow to golden brown, often with a slight greenish tinge, darkening on exposure to a reddish brown; sapwood 2 to 3 in. wide, pale pink, distinct. Texture moderately coarse, grain interlocked; lustrous; disagreeable odor when freshly cut, but without odor or taste when dry.

Weight: Basic specific gravity (ovendry weight/green volume) 0.80; air-dry density about rundown 60 pcf.

Mechanical Properties: (2-cm standard)

Moisture content Bending strength Modulus of elasticity Maximum crushing strength

(%) (Psi) (1,000 psi) (Psi)

Green (9) 14,700 1,850 8,230

12% 20,300 2,330 12,380

12% (44) 25,800 2,560 14,200

Janka side hardness 2,540 lb for green material and 2,780 lb for dry. Amsler toughness about 400 in.-lb at 12% moisture content (2-cm specimen).

Drying and Shrinkage: Dries slowly with marked tendency to surface and end check but warping is not serious. Kiln schedule T2-C2 is suggested for 4/4 stock and T2-C1 for 8/4. Shrinkage green to ovendry: radial 6.0%; tangential 8.8%; volumetric 12.6%.

Working Properties: Rather difficult to saw with some dulling, difficult to work with hand and machine tools, tearing of interlocked grain in planing, turns well, glues and finishes well.

Durability: Heartwood is very durable and highly resistant to termite attack; sapwood liable to powder-post beetle attack. Resistant to marine borers, excellent weathering properties, and has high resistance to wear.

Preservation: Heartwood extremely resistant, sapwood resistant.

Uses: Marine piling and dockwork, heavy-duty flooring, railroad crossties, heavy construction.

Additional Reading: (3), (9), (17), (44)