Gossweilerodendron balsamiferum

Agba

Family: Leguminosae

Other Common Names: Achi, Egba, Emongi (Nigeria), Tola blanc (Congo-Brazzaville), Tola branca (Angola), N'Tola (Zaire).

Distribution: Tropical West Africa from Nigeria southwards to the Congo basin, scattered or in local pockets, favoring deep soil and plenty of moisture.

The Tree: Reaches a height of 200 ft; boles clear and straight to 80 to 100 ft and more; trunk diameters 5 to 8 ft. Trunk wounds yield a thick gummy exudate.

The Wood:

General Characteristics: Heartwood yellowish- to pinkish brown, darkening on exposure; sapwood 4 in. wide, slightly lighter in color, not well demarcated. Texture moderately fine and even; grain straight to slightly wavy or interlocked; luster high; resinous odor; large resin deposits may accumulate in shakes near the heart.

Weight: Basic specific gravity (ovendry weight/green volume) about 0.40; air-dry density 30 pcf.

Mechanical Properties: (2-cm standard)

Moisture content Bending strength Modulus of elasticity Maximum crushing strength

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

Green (9) 7,500 870 3,520

12% 11,800 1,100 6,270

12% (46) 9,500 920 4,800

Janka side hardness 620 lb for green material and 740 lb for dry. Amsler toughness 106 in.-lb for dry material (2-cm specimen).

Drying and Shrinkage: Dries fairly rapidly with very little tendency to warp or check. Boards must be separated by stickering immediately after sawing to prevent resin exudates sticking them together. Kiln schedule T10-D5S is suggested for 4/4 stock and T8-D4S for 8/4. Shrinkage green to 12% moisture content: radial 1.5%; tangential 3.0%. Movement in service is rated as small.

Working Properties: Saws readily and works easily with hand and machine tools, gums may collect on sawteeth and cutters, good gluing properties, moderately good steam-bending characteristics.

Durability: Heartwood is rated as durable, fairly resistant to termite attack.

Preservation: Heartwood resistant to impregnation; sapwood permeable.

Uses: A general purpose timber, furniture, joinery, boatbuilding, light construction millwork, core stock, plywood, domestic flooring.

Additional Reading: (3), (9), (13), (46)