Tropical wood · Tropical America
Kurokai wood
Kurokai (Protium spp., family Burseraceae) is a tropical timber from tropical America. Dry, its Janka hardness is 720–1,280 lbf (3,203–5,694 N), and air-dry it weighs about 33–45 lb/ft³ (529–721 kg/m³). The figures are from the USDA Forest Products Laboratory's Tropical Timbers of the World, pp. 255–256.
Other names, by country: Latilla, Pom (Mexico), Alcanfor, Fontole (.Honduras), Caraño, Chutra (Panama), Anime, Caraño (Colombia), Bálsamo, Tacamahaco (Venezuela), Kurokai (Guyana), Bois encens (French Guiana), Breu branco, Breu preto, Sucuriúba (Brazil).
Key numbers
- Janka hardness, dry
- 720–1,280 lbf (3,203–5,694 N)
- As printed: “Janka side hardness at 12% moisture content ranged from 720 lb to 1,280 lb.”
- Air-dry density
- 33–45 lb/ft³ (529–721 kg/m³)
- Basic specific gravity
- 0.45–0.61 oven-dry weight, green volume
- As printed: “Basic specific gravity (ovendry weight/green volume) varies with species from 0.45 to 0.61; air-dry density 33 to 45 pcf.”
- Shrinkage, green to oven-dry
- 6.8% tangential
- Radial 4.2%, volumetric 10.7%
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 | 11,000 psi (76 MPa) | 1.47 million psi (10.1 GPa) | 5,280 psi (36 MPa) |
| 12% MC | 16,850 psi (116 MPa) | 1.77 million psi (12.2 GPa) | 9,200 psi (63 MPa) |
| Green | 9,300 psi (64 MPa) | 1.51 million psi (10.4 GPa) | 4,370 psi (30 MPa) |
| 12% MC | 11,800 psi (81 MPa) | 1.65 million psi (11.4 GPa) | 6,960 psi (48 MPa) |
| 12% MC | 15,700 psi (108 MPa) | 1.86 million psi (12.8 GPa) | 8,700 psi (60 MPa) |
A dash means the sheet prints no value; none is filled in.
What the data sheet says
- Color, grain and texture
- Heartwood brown or reddish-brown, sometimes with irregularly spaced darker brown lines; not always sharply demarcated from the pale buff to pinkish sapwood. Texture varies from rather fine to fairly coarse; luster rather high; grain straight to very irregular and interlocked; dry specimens without distinctive odor or taste. Silica reported for some species.
- Working properties
- Logs should be debarked prior to sawing to avoid resin accumulation on cutters and equipment. Dry wood works easily and rates fair to good in all operations. Cuts easily into veneers but tends to buckle on drying. Some species abrasive because of silica content.
- Durability
- Generally reported to have low resistance to attack by decay fungi and vulnerable to dry-wood termites. No appreciable resistance to marine borers.
- Uses
- Furniture, millwork, veneer and plywood, general construction, particleboard, a possible substitute for birch. Incense-like resin obtained from wounds to the bark and marketed as "elemi".
- Where it grows
- Throughout tropical America but most abundantly represented in the Amazon basin; frequent in the marsh forests of Guyana.
Quoted from Tropical Timbers of the World, pp. 255–256, 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 kurokai against other woods on hardness, weight, movement and color, every figure from the Wood Handbook.