Bete

Bete (Mansonia altissima)
Mansonia, Ofun, Aprono

Origin:

Beta trees grow in West Africa – from the Ivory Coast to Cameroon. The main distribution area for this species is the Brong – Ahafo province in Ghana. Within the natural range, the status of the species in question varies; for example, in Ghana the wood is regularly harvested and exported, while in Côte d'Ivoire it is under protection.

Tree habit:

Beta trees are slender, can grow to a height of 30-35 m (sometimes more) and reach a trunk diameter of up to 0.8 m. The trunk in mature plants is devoid of branches up to a height of about 20 m. It is usually straight and cylindrical in shape. 

Structure type:

Diffuse-vascular, the vessels are evenly spaced across the width of the annual increments, usually 2-3 each in radial rows. The diameter of the vessel members ranges from 0.06 to 0.14 mm. There are between 7 and 65 vessels per 1 mm² of cross-section (average 30).

Sapwood:

Narrow (2 to 5 cm wide), cream-coloured.

Heartwood:

Depending on the habitat, it can range in colour from yellowish brown to dark greyish brown, with dark strands often present. When exposed to light, heartwood darkens, becoming similar to that of the North American walnut or walnut.     

Fragrance:

During working, it gives off an insipid, irritating smell that quickly fades away. Treated wood does not emit an odour.

Pattern:

Beta is a sclerophyllous species with poorly distinguishable annual increments – best seen in cross-section. These increments often have a wavy course. The fine vessels present in the wood are almost invisible, as are the narrow medullary rays. The woody parenchyma is present in very small amounts in the form of diffuse apotracheal parenchyma, forming short, tangential lines. It is difficult to see even in microscope preparations. Upon close inspection of the tangential section, the delicately outlined, regular, stratified arrangement of structural elements is notable. The wood is generally straight-fibred.     

Working:

Easy, both by hand and by machine, but requires special safety measures due to its high toxicity. Bete wood machine cuts very well.   

Joining:

Not difficult either with nails, screws or adhesives. The tannins in the wood discolour blue on prolonged contact with metals.

Finishing:

Smooth surfaces are achieved with sanding and polishing.

Intended use:

widely used in carpentry, stairs, furniture, doors, veneers, boatbuilding – oars, rudders etc., musical instruments.

Availability
65 mm – KD – LS block-cut – FAS grade

• Mechanical properties: Bete is a medium hardwood. The grain is rather straight and the structure smooth.
• Modulus of elasticity: 14 GPa
• Tangential shrinkage: 7.4%
• Radial shrinkage: 4.6%
• Specific gravity: 660 kg/m³ (12%)
• Durability: species resistant to destructive fungal attack
• Dry wood pests: resistant – risk limited to sapwood penetration
• Protections: class 4 – non-accepting
• In addition: contact with the ground not recommended, resistant to external conditions