Tropical wood · Africa
Bombax wood
Bombax (Bombax spp., family Bombacaceae) is a tropical timber from Africa. Dry, its Janka hardness is 400 lbf (1,779 N), and air-dry it weighs about 30 lb/ft³ (481 kg/m³). The figures are from the USDA Forest Products Laboratory's Tropical Timbers of the World, pp. 345–346.
Other names, by country: Alone, Ogoumalanga (Gabon), Msufi-mwitu, Mfume (Tanzania), Meguza (Mozambique), Kapokier (Senegal).
Key numbers
- Janka hardness, dry
- 400 lbf (1,779 N)
- Green: 390 lbf (1,735 N)
- As printed: “Janka side hardness 390 lb for green material and 400 lb for dry.”
- Air-dry density
- 30 lb/ft³ (481 kg/m³)
- Basic specific gravity
- 0.40 oven-dry weight, green volume
- As printed: “Basic specific gravity (ovendry weight/green volume) about 0.40; air-dry density 30 pcf.”
- Shrinkage, green to oven-dry
- 8.1% tangential
- Radial 4.9%
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 4 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 | 4,310 psi (30 MPa) | 0.73 million psi (5 GPa) | 2,380 psi (16 MPa) |
| 12% MC | 6,790 psi (47 MPa) | 0.88 million psi (6.1 GPa) | 4,460 psi (31 MPa) |
| 12% MC | 10,800 psi (74 MPa) | 1.05 million psi (7.2 GPa) | 5,400 psi (37 MPa) |
| 12% MC | 6,300 psi (43 MPa) | — | 4,700 psi (32 MPa) |
A dash means the sheet prints no value; none is filled in.
What the data sheet says
- Color, grain and texture
- Heartwood pale reddish-brown, yellowish-brown, or light brown with a purplish tint, sometimes with darker markings; sapwood whitish, not always sharply differentiated. Texture medium to coarse; grain usually straight; without luster; sometimes with gum veins. Janka side hardness 390 lb for green material and 400 lb for dry. Amsler toughness 94-111 in.-lb for dry material (2-cm specimen). 345
- Working properties
- Usually saws easily and works well with hand and machine tools but cutters must be kept sharp; glues and finishes well; easy to rotary peel veneers.
- Durability
- Heartwood perishable, not resistant to termite attack; sapwood vulnerable to powder-post beetle attack. Rapid extraction and coversion necessary to prevent deterioration from stain, decay, and insect attack.
- Uses
- Plywood core stock, block board, boxes and crates, furniture components.
- Where it grows
- West Africa and extending eastward into Tanzania; found in savanna and secondary forests as well as dense rain forests.
Quoted from Tropical Timbers of the World, pp. 345–346, 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 bombax against other woods on hardness, weight, movement and color, every figure from the Wood Handbook.