Afromosia

Afromosia (Periocopsis elata van Meeuwen)

Origin: Africa

Nomenclature:

• Polish: afromozja
• English: afromosia, kokrodua
• French: afromosia, kokrodua, assamela, oleo pardo
• German: Afromosia, Kokrodua
• names used in other countries: in Cameroon – obang, in the Democratic Republic of Congo – bohala, bohele, mohele, ole, afrormosia, in Ghana – kokrunda, in Côte d'Ivoire – assamela

Availability
27 mm – KD – SE edged – FAS grade – 215 mm fix
52 mm – KD – SE edged – FAS grade

Occurrence:

Afromosia trees are found in western and central Africa, in Côte d'Ivoire, Nigeria, Ghana, Cameroon, Democratic Republic of Congo.  

Tree habit:

Afromosia trees, depending on habitat conditions, reach a height of 30 - 45 m (exceptionally 50 m) and a trunk diameter of d0 0.6 - 1.0 m (occasionally up to 1.5 m). The prominent, branchless trunk is about 15-25 m high. 

Structure type:

Deciduous diffuse-vascular, large vessels are arranged singly or in groupings of 2-3.

Sapwood:

Narrow, yellowish white, 1 to 3 cm wide.

Heartwood:

Of a pastel, even, yellow-brown colour, sometimes with a greenish shade.

Fragrance:

No fragrance.

Pattern:

Annual increments are barely visible and only on the cross-section. In this cross-section, the pattern is complemented by narrow parenchyma streaks running parallel to the annual increment boundaries, and large vessels visible as darker dots. On longitudinal sections, these vessels form fine indentations. There is a striped fibre twist on the radial section. Areas with alternating deflected fibres are narrow. This wood has a stratified structure, visible as regularly arranged medullary rays (stratified) on the tangential cross-section.

Typical defects:

stripy fibre twist.

Physical properties of Afromosia wood:

According to a six-grade scale, afromosia is a heavy wood (Class II). The average density for the air-dry condition (for wood with a moisture content of approximately 12%) is 740 kg/m³. The wood in question is characterised by a low fibre saturation point moisture content of 20% and fairly low shrinkage values. According to Monin's classification, afromosia belongs to the medium shrinkage wood. The anisotropy of shrinkage has an average value of 1.9. 

Mechanical properties of Afromosia wood:

Associated with the high density of wood are high mechanical properties. However, their reduction is influenced by the presence of stripy fibre twist. For example, the average compressive strength is approximately 66 MPa and the static bending strength is approximately 120 MPa. The wood has an average modulus of elasticity of up to 13.0 GPa.

Hardness:

Heartwood is resistant to impregnation with wood preservatives. However, this is not necessary, due to its high natural durability. According to PN-EN 350-2:2000, the durability of heartwood against fungi on a five-point scale is 1-2, which means very durable to durable wood. Sapwood is perishable and in many cases a waste.

Drying:

It is slow, but without much risk of cracking or deformation.

Working:

It is hampered by the presence of a striped fibre twist. When deflected at different angles, the wood fibres have a tendency to pull out.

Sanding:

This wood sands and polishes well. No data on the harmfulness of wood dust. Adequate dust extraction is required.

Joining:

Good adhesion. The following adhesives can be used: polyurethane-epoxy, two-component polyurethane, one-component polyurethane, hybrid. When connecting with screws and nails, pre-drilling is required. Fasteners containing iron are not recommended due to the risk of ink staining.

Finishing:

A properly prepared surface accepts paints and varnishes well. Dark discolouration in contact with water-based varnishes is possible. It is then necessary to use special primers designed for wood containing tannins.

Intended use:

Recommended use in parquet flooring - in the domestic market, afromosia wood is mainly available in the form of flooring slats and flooring sandwich elements. In the latter, it forms the upper wear layer, visible on the floor face. Due to its relatively high density and associated hardness, this wood can be used for floors not only in living rooms, but also in more heavily used areas such as corridors.
Other uses - afromosia wood, due to its favourable strength characteristics, is used for structural elements in civil engineering and shipbuilding, as well as for semi-finished furniture, especially for cabinet furniture. Smaller pieces of wood are used in woodworking, often with other colour-contrasting species, e.g. for making caskets and jewellery. Afromosia wood is also used in boatbuilding. 
 

Similar species:

Other Afromosia species from Africa, e.g. Afromosia angolensis Harms, Afromosia laxiflora Harms. There is also some visual similarity to movingui wood and, to a lesser extent, to teak and ovangkol.

Notes:

The striped twist of the fibres makes working more difficult.

Trivia:

Afromosia is one of the endangered tree types with a declining population. In selected African countries, some Afromosia species are protected and their trade is restricted by regulations under the Washington Convention (on International Trade in Endangered Species of Wild Fauna and Flora). Therefore, when buying this wood, it is worth making sure that it comes from a legal source where good forest management is carried out.

• Mechanical properties: Afromosia is worked well. Bonding and sanding are good, but nailing at risk of cracking (predrilling required). Wood should not come into contact with metal in wet conditions as this causes discolouration.
• Modulus of elasticity: 13 GPa
• Tangential shrinkage: 5.9%
• Radial shrinkage: 3.2%
• Specific gravity: 740 kg/m³ (12%)
• Durability: species resistant to destructive fungal attack
• Dry wood pests: resistant – risk limited to sapwood penetration
• Protections: class 4 – non-accepting
• Additionally: resistant to contact with soil, fresh water or high humidity