USDA Forest Service
Forest Products Laboratory
One Gifford Pinchot Drive
Madison, WI 53705-2398
Wood Technical Fact Sheet
and G. thompsonii
Other Common Names: Bossy (Ivory Coast), Kwabohoro (Ghana), Obobo (Nigeria), Edoucie (Cameroon).
Distribution: The range of both species overlaps in Ivory Coast, Ghana, and southern Nigeria. G. cedrata extends into the Cameroons, G. thompsonii reaches into Liberia.
The Tree: Reaches a height of 160 ft; boles are long, straight, and cylindrical; trunk diameters are about 3 to 4 ft above buttresses.
General Characteristics: Heartwood pinkish brown, darkening on exposure; sapwood variable in width, pale in color, often well demarcated. Texture medium to fine; grain straight, wary, or interlocked; lustrous; both woods contain gums. Silica often present in G. cedrata. Cedary odor sometimes persists. Dust may irritate skin and mucous membranes.
Weight: Basic specific gravity (ovendry weight/green volume) about 0.48; air-dry density 36 pcf.
Mechanical Properties: (2-cm standard)
Moisture content Bending strength Modulus of elasticity Maximum crushing strength
(%) (Psi) (1,000 psi) (Psi)
Green (9) 10,800 1,290 5,140
12% 14,900 1,370 7,720
Green (9) 12,400 1,540 6,260
12% 15,500 1,570 8,680
12% (44) 14,700 NA 7,750
Janka side hardness about 1,000 lb for dry material. Amsler toughness 230 in.-lb for dry material (2-cm specimen).
Drying and Shrinkage: Dries fairly rapidly with little tendency to warp, may require some care to prevent checking. Kiln schedule T6-D2 is suggested for 4/4 stock and T3-D1 for 8/4. Shrinkage green to 12% moisture content: radial 2.0 to 2.5%; tangential 3.5 to 4.0%. Movement in service is rated as small.
Working Properties: Works fairly well with hand and machine tools, some picking of grain if interlocked, slight to moderate blunting of cutters, glues well, takes a good polish, good to moderately good steam-bending properties. Sometimes difficult to handle because of gum. Dust may be irritating.
Durability: Heartwood ratings vary from durable to moderately durable; moderately resistant to termite attack.
Preservation: Heartwood highly resistant to impregnation; sapwood permeable.
Uses: Furniture, joinery, paneling, boatbuilding, decorative veneers, turnery, flooring.
Additional Reading: (3), (9), (44)