Doussie

Doussie (Afzelia sp.)

Origin: Africa

Nomenclature:

• Polish: zakrwin, afzelia, lingue, doussie
• English: Afzelia
• French doussie
• German: Afzelia
• names used in other countries: in Spain-tindalo, in Portugal- chanfuta, in Angola- uvala and nkokongo, in Ghana- papao, in Cameroon- m'bango and doussie, in Nigeria- aligna, apa, aryan, odo, Côte d'Ivoire: azodu and lingue, Congo: sifu, belungug, bolengu, bombanga, sungula, Mozambique: chanufta and mussacossa, Tanzania: mbembakofi and mkora

Availability
Doussie (Afzelia Pachyloba)
26 mm – KD – LS block-cut – FAS grade

Doussie (Afzelia Bipidensis) wood with better characteristics
27 mm – KD – SE edged – FAS grade
52 mm – KD – LS unedged – FAS grade

Occurrence:

The wood is harvested from several species of trees of the genus Afzelia. The trees Afzelia africana Smith ex Pers, Afzelia bipindensis Harms and Afzelia pachyloba Harms are native to west and central Africa, and Afzelia quanzenzis Welw. mainly from the eastern part of the continent. Trees of the genus Afzelia grow in different habitats and different types of plant groupings. They can be found up to an altitude of 1,300 m above sea level, both in the shady thicket of rainforests and in light-filled savannahs or coastal forests exposed to strong winds. These plants grow well in light drying soils, producing a fairly deep root system. Populations of these relatively slow-growing trees can be found in Guinea, Liberia, Nigeria, Cameroon, Congo, Angola, Uganda, Kenya, Mozambique and Côte d'Ivoire.

Tree habit:

The largest of the doussie trees reach heights of up to about 35 m (or even 40 m) and a butt diameter of up to 1.2 m. The trunk is usually quite straight, cylindrical with small flutes reaching up to 1 m in height for exotic species. In mature trees, the branchless part of the trunk is on average about 15-20 m long.

Structure type:

Diffuse-vascular; vessels occur singly or in groupings of 2-3.

Sapwood:

Narrow (2 to 5 cm wide) is noticeably lighter in colour, has an uninteresting colouring reminiscent of dried grass and is treated as waste wood.

Heartwood:

Has a warm, orange-brown colour, which gradually darkens with the passage of time – under the influence of light and oxygen in the air – to resemble the colour of mahogany wood. The darkening process takes about nine months in a closed room. After that, the colour changes are essentially imperceptible.

Fragrance:

When sawing, the fresh wood gives off a rather unpleasant, nauseating odour, which disappears quite quickly.

Pattern:

annual increments are mostly invisible. In wood from the subtropical zone with marked seasons, the outline of darker lines-areas of more compact (darker) wood with fewer vessels can be seen on the cross-section. On all cross-sections, the wood pattern is enriched by large vessels (optically enlarged by the winged parenchyma), which are often filled with a whitish or yellowish-brown substance in heartwood. The wood often has an irregular, striped fibre twist.

Typical defects:

Fibre twist.

Physical properties of Doussie wood:

The average density for the air-dry condition (for a moisture content of approximately 12%) is 750 kg/m³. Doussie belongs to the heavy wood category (class II). It is characterised by its low fibre saturation point moisture content (only 20%) and very low shrinkage values, as well as its extremely low anisotropy – 1.4. According to Monin's classification, doussie is a low-shrinkage wood – its volume shrinkage is below 10% (on average about 8.2%).

Mechanical properties of Doussie wood:

Associated with the relatively high density of the wood are high mechanical properties. For example, the average compressive strength is 70 MPa and the static bending strength is 110 MPa. The hardness, which averages 75 MPa on the cross-section, is favourable. The reduction in mechanical properties is influenced by the layout of the fibres, which are often deviated from a perfectly longitudinal direction. Deviated fibre wood has a significantly lower modulus of elasticity (about 11 GPa) than straight-fibre wood (over 17 GPa).

Hardness:

Heartwood has a high natural durability even when in contact with the ground or the water environment. The natural durability of heartwood against fungi is 1, which means very durable wood. It is a wood resistant to termite attack, suggesting an equally high natural resistance to domestic xylophages.

Drying:

It dries well (it does not tend to crack or warp), but the process must be carried out slowly.

Working:

The wood is generally easy to work: sawing, milling, drilling (sometimes hampered by the striped fibre twist that occurs).

Sanding:

Sanding and polishing are no problem. There is only more rapid wear of the abrasives, due to the mineral deposit content. However, it should be borne in mind that appropriate health and safety requirements should be observed in technological operations where wood dust is generated. Doussie wood dust can cause dermatological problems in some people, irritate the respiratory tract and cause skin sensitisation. 

Joining:

Bonding is slightly hindered by the non-structural substances content. The joining of doussie wood with nails and screws should be preceded by drilling.

Finishing:

Due to the content of non-structural substances, this wood is more difficult to absorb impregnating agents and paint/varnish agents, but on the other hand, also other substances with adverse effects, such as acids. If water-based varnishes are used, dark discolouration may occur, so special primers designed for wood containing tannins should be used. Direct coating with liquid wax or water-based varnish can cause a whitish, soapy discharge to appear, and the solidification itself will begin to lengthen. It is therefore advisable to use polyurethane varnishes or to carry out a test before actual installation or varnishing. To avoid these difficulties, instead of coating the surface with an airtight chemical agent, oiling and appropriate care products will suffice. The open structure allows the wood to "breathe" which, as a result of the exchange of moisture with the air, provides more favourable microclimatic conditions in the rooms.

Intended use:

Recommended parquet applications – thanks to its considerable hardness and associated low abrasion and dimensional stability, it performs well in this application and is considered by many to be the ideal parquet material. Aesthetic qualities are also an advantage of this wood. The rich appearance of the patterned substrate of this wood emphasises the sophistication of the rooms. It is also used for heavily loaded surfaces in sports facilities. A good example of this application is the Olympic cycle track in Munich, Bavaria. Domestically, this wood is usually sold as solid parquet boards and of considerable size, as well as flooring slats and lamella flooring.
Other uses - doussie wood is used for structural elements, exterior joinery (doors, windows) and interior fittings such as panelling and furniture. It is also used for outdoor structures (fences, gates, gazebos) and garden furniture, as well as in boatbuilding. In terms of dimensional stability, this wood even surpasses teak wood as a substitute. It was used in the shipbuilding industry and in the manufacture of, for example, dashboards, control panels, laboratory tables and benches. Nowadays, it is used to make wood accessories (jugs, bowls, caskets, pen holders, key rings). It is also used as a material for the interior trim of exclusive cars and aircraft.

Similar species:

Light palisanders (Dalbergia sp.) and tarara amarilla wood.

Notes:

Doussie is considered the ideal parquet material and fully deserves the name. However, it is important to bear in mind the harmfulness of dust and the use of appropriate finishing agents.

Trivia:

In the most general terms, the number of tree species yielding doussie wood can be limited to the four most important: Afzelia africana Smith ex Pers., Afzelia bipindensis Harms, Afzelia pachyloba Harms, Afzelia quanzenzis Welw. The best wood is considered to be the so-called doussie lingua harvested from Afzelia bipindensis Harms trees, which is characterised by the presence of distinct yellow staining in the vessels. In wood from other species, this colouration is more whitish.

• Mechanical properties: Doussie is a hard and rather heavy wood. It dries slowly especially in the thicker sections with a tendency for cracking to occur. The wood is rather heavy to work with, but in the end is susceptible to polishing.
• Modulus of elasticity: 14.5 GPa
• Tangential shrinkage: 4.6%
• Radial shrinkage: 3.2%
• Specific gravity: 750 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, naturally resistant to external conditions