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.
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)
3. Bolza, E., and W.G. Keating. 1972. African timbers-the properties, used, and characteristics of 700 species. CSIRO. Div. of Build. Res., Melbourne, Australia.
17. France: Bois For. Trop. 1955. Okan (Adoum) (Cylicodiscus gabunensis). Bois For. Trop.
9. Farmer, R. H. 1972. Handbook of hardwoods. H. M. Stationery Office. London.
44.Sallenave, P. 1955. Proprietes et mecaniques des bois tropicaux de l'union Francaise. Pub. Centre Tech. For. Trop. No. 8.
From: Chudnoff, Martin. 1984. Tropical Timbers of the World. USDA Forest Service. Ag. Handbook No. 607.