Tropical wood · Africa
Pterygota wood
Pterygota (Pterygota spp., family Sterculiaceae) is a tropical timber from Africa. Dry, its Janka hardness is 940–970 lbf (4,181–4,315 N), and air-dry it weighs about 35–43 lb/ft³ (561–689 kg/m³). The figures are from the USDA Forest Products Laboratory's Tropical Timbers of the World, pp. 495–496.
Other names, by country: Kyere, Awari, Okyere (Ghana), Koto (Ivory Coast), Poroposo, Kefe (Nigeria).
Key numbers
- Janka hardness, dry
- 940–970 lbf (4,181–4,315 N)
- Green: 670–790 lbf (2,980–3,514 N)
- As printed: “Janka side hardness 670-790 lb for green material and 940-970 lb for dry.”
- Air-dry density
- 35–43 lb/ft³ (561–689 kg/m³)
- Basic specific gravity
- 0.47–0.56 oven-dry weight, green volume
- As printed: “Basic specific gravity (ovendry weight/green volume) 0.47-0.56; air-dry density 35-43 pcf.”
- Shrinkage, green to oven-dry
- 11.4% tangential
- Radial 5.7%, volumetric 15.0%
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 5 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 | 10,600 psi (73 MPa) | 1.27 million psi (8.8 GPa) | 5,130 psi (35 MPa) |
| 12% MC | 16,100 psi (111 MPa) | 1.67 million psi (11.5 GPa) | 8,400 psi (58 MPa) |
| Green | 8,300 psi (57 MPa) | 1.08 million psi (7.4 GPa) | 3,870 psi (27 MPa) |
| 12% MC | 12,300 psi (85 MPa) | 1.34 million psi (9.2 GPa) | 6,300 psi (43 MPa) |
| 12% MC | 17,800 psi (123 MPa) | 2.14 million psi (14.8 GPa) | 8,450 psi (58 MPa) |
A dash means the sheet prints no value; none is filled in.
What the data sheet says
- Color, grain and texture
- Wood pale yellow to a creamy-white with little differentiation between sapwood and heartwood. Texture rather coarse; grain straight to interlocked; green material has an unpleasant smell which disappears on drying; high rays give a conspicuous flecked figure; commonly with small knot clusters.
- Working properties
- Works fairly easily with hand and machine tools, a cutting angle of 20 degrees is suggested to reduce tearing of interlocked grain in planing, glues and nails satisfactorily, peels and slices into veneers satisfactorily.
- Durability
- Heartwood is not durable and is liable to termite attack; sapwood liable to powder-post beetle attack. Logs are prone to stain and insect attack requiring rapid removal from the forest or a chemical treatment.
- Uses
- Furniture components, joinery, general carpentry, boxes and crates, plywood.
- Where it grows
- Common in tropical evergreen and mixed deciduous forests of West Africa.
Quoted from Tropical Timbers of the World, pp. 495–496, a USDA Forest Products Laboratory work in the public domain.
Work it out for your project
- Rank woods for furniture with the species picker
Weigh pterygota against other woods on hardness, weight, movement and color, every figure from the Wood Handbook.