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What is Bilinga wood?
Definition
Bilinga wood is a durable hardwood species derived from the Bilinga tree, scientifically known as Nauclea diderrichii or Nauclea gilletii. This tree species belongs to the Rubiaceae family and grows in tropical West Africa. Bilinga wood is known for its unique golden yellow to orange-yellow color, which darkens over time to orange-red to golden brown. It has a distinctly identifiable, pale yellow to white sapwood and is recognizable by the striped pattern on the quarter-sawn surface, caused by the interlocked grain.
Interesting Facts about Bilinga Wood
- Bilinga is also known as 'Aloma' in Germany and 'Opepe' in England.
- The tree can reach a height of 30 to 40 meters with a diameter of up to 1.20 meters.
- The trunk is cylindrical, usually slender and very straight, without buttresses.
- The bark is gray-brown and flaky, sometimes orange-yellow in color and often cracked.
- The fruits of the Bilinga tree are edible, with a fleshy and fragrant pulp.
- Bilinga wood has a density similar to true hickory but is slightly less strong.
- It is one of the few tropical hardwoods that is naturally suitable for use in seawater (use class 5).
Properties and Applications
Versatility
Bilinga wood is ideal for:
- Road and water construction projects (bridges, docks, railings)
- Park benches, fences, gates, and pergolas
- Decking boards (with specific profiles and artificial drying to minimize warping)
- Construction (indoor and outdoor)
- Water construction (lock gates, retaining structures, bridge decks)
- Shipbuilding (decking and flooring)
- Heavy industrial flooring
- Veneer and furniture work
Durability
Bilinga wood has a durability class 1 certification, making it extremely durable. It is highly resistant to fungi, termites, and dry wood borers. In temperate climates, the wood is very durable against fungi and resistant to dry wood borers and termites.
Workability
Despite its high hardness, Bilinga can be machined quite well. For a smooth surface, it is important to work with a small cutting angle due to the strong interlocked grain. Sharp tools are essential because of the dulling effect of dried Bilinga wood.
Certification and Quality
- CE marking: Bilinga wood can be supplied with a CE marking according to the NEN 5493 standard.
- Strength class: D50 according to NEN-EN 338.
- Quality classes: A, B, C according to the NEN 5480 standard, with class A setting the highest requirements for strength and appearance.
Technical Specifications
| Property | Value |
|---|---|
| Green weight (kg/m3) | 1000 – 1100 |
| Specific weight at 12% moisture content (kg/m3) | 760 (heavy) |
| Volumetric swelling for 1% moisture change | 0.55% (large) |
| Total tangential swelling | 8.0% |
| Total radial swelling | 4.7% |
| Compressive strength (N/mm2) | 62 |
| Static bending strength (N/mm2) | 134 |
| Modulus of elasticity (N/mm2) | 11800 |
Natural Durability and Treatability
| Property | Classification |
|---|---|
| Fungi | Class 1 - durable |
| Dry wood borers | Durable |
| Termites | Class D - durable |
| Treatability | Class 2 - moderately permeable |
| Use class assured by natural durability | Class 4 - in contact with soil or fresh water |
| Suitable for use class 5 | Yes |
Ecology and Biology
The Bilinga tree is an evergreen species that grows in tropical evergreen and semi-deciduous forests. The seeds are dispersed by animals from August to December. Its range extends from Sierra Leone in the north to Angola in the south and Uganda in the east.
Frequently Asked Questions (FAQ)
What is the color of Bilinga wood?
Bilinga wood has a unique golden yellow to orange-yellow color, which darkens over time to orange-red to golden brown.
Is Bilinga wood suitable for outdoor use?
Yes, Bilinga wood is highly suitable for outdoor use due to its high durability (class 1) and resistance to fungi, termites, and dry wood borers.
How does Bilinga wood machine?
Despite its hardness, Bilinga machines quite well. It is important to use sharp tools and a small cutting angle due to the strong interlocked grain.
Can Bilinga wood come into contact with seawater?
Yes, Bilinga is one of the few tropical hardwoods that is naturally suitable for use in seawater (use class 5).
What are the most common applications of Bilinga wood?
Bilinga is widely used in road and water construction, outdoor furniture, decking boards, heavy constructions, and shipbuilding.