Tropical wood · Africa
Okan wood
Okan (Cylicodiscus gabunensis, family Leguminosae) is a tropical timber from Africa. Dry, its Janka hardness is 2,780 lbf (12,366 N), and air-dry it weighs about 60 lb/ft³ (961 kg/m³). The figures are from the USDA Forest Products Laboratory's Tropical Timbers of the World, pp. 379–380.
Other names, by country: Denya (Ghana), Edum (Gabon), Adoum, Bokoka (Cameroon), Bouémon (Ivory Coast).
Key numbers
- Janka hardness, dry
- 2,780 lbf (12,366 N)
- Green: 2,540 lbf (11,298 N)
- As printed: “Janka side hardness 2,540 lb for green material and 2,780 lb for dry.”
- Air-dry density
- 60 lb/ft³ (961 kg/m³)
- Basic specific gravity
- 0.80 oven-dry weight, green volume
- As printed: “Basic specific gravity (ovendry weight/green volume) 0.80; air-dry density about 60 pcf.”
- Shrinkage, green to oven-dry
- 8.8% tangential
- Radial 6.0%, volumetric 12.6%
One source: USDA Forest Products Laboratory, Tropical Timbers of the World (Chudnoff, 1979 edition), the only published source read for this wood
Strength
Bending strength is the modulus of rupture (MOR); stiffness is the modulus of elasticity (MOE); crushing strength is compression parallel to the grain. The sheet collects these from published tests: it prints 3 data sets, from different tests and sources, so they can differ widely; all are shown, in the sheet's order, each at the moisture content printed beside it, never restated as 12%.
| Moisture | Bending strength (MOR) | Stiffness (MOE) | Crushing strength |
|---|---|---|---|
| Green | 14,700 psi (101 MPa) | 1.85 million psi (12.8 GPa) | 8,230 psi (57 MPa) |
| 12% MC | 20,300 psi (140 MPa) | 2.33 million psi (16.1 GPa) | 12,380 psi (85 MPa) |
| 12% MC | 25,800 psi (178 MPa) | 2.56 million psi (17.7 GPa) | 14,200 psi (98 MPa) |
A dash means the sheet prints no value; none is filled in.
What the data sheet says
- Color, grain and texture
- Heartwood yellow to golden brown, often with a slight greenish tinge, darkening on exposure to a reddish-brown; sapwood 2-3 in. wide, pale pink, distinct. Texture moderately coarse, grain interlocked; lustrous; disagreeable odor when freshly cut, but without odor or taste when dry.
- Working properties
- Rather difficult to saw with some dulling, difficult to work with band 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.
- Uses
- Marine piling and dockwork, heavy-duty flooring, railroad crossties, heavy construction.
- Where it grows
- A large tree 180-200 ft in height, bole straight, cylindrical, and clear to 80 ft; trunk diameters about 3-4 ft but may reach 8-10 ft above short buttresses.
Quoted from Tropical Timbers of the World, pp. 379–380, a USDA Forest Products Laboratory work in the public domain.
Work it out for your project
- Rank woods for flooring with the species picker
Weigh okan against other woods on hardness, weight, movement and color, every figure from the Wood Handbook.