Zebrano

Zebrano (Microberlinia brazzavillensis)

Zingana, Zebra wood

Origin:

Zebrano trees grow in the humid equatorial forests of Africa, in countries along the Gulf of Guinea. The area of natural occurrence includes Cameroon, Equatorial Guinea, Gabon and Congo. Within Cameroon, these trees mainly grow in the south of the Mungo Mountains, while in Gabon they grow on the edge of the FemanVaz lagoon, and in Congo they grow in part of the forest massif of the Congo River basin, bordering Cameroon.

Tree habit:

Under favourable growth conditions, zebrano trees reach 30-40 m in size. The trunk is straight, cylindrical, with small flutes, topped by a strongly branched crown starting at 15-20 m.

Structure type:

Diffuse-vascular, vessels 0.11-0.27 mm in diameter are evenly distributed (singly or in clusters of 2-3).  

Sapwood:

Wide (up to 10 cm), grey-white in colour, it is clearly delimited from heartwood zone.

Heartwood:

Of variable colour, with a distinctive streaked pattern. The lighter white-olive or white-reddish background shows dark stripes and lines in grey-brown or even black. The darker strands of variable width generally run parallel (along the fibres), at intervals of 2-6 or 10 mm, sometimes merging or separating.     

Fragrance:

Freshly sawn wood gives off a characteristic smell similar to ochre or sulphur, which disappears over time. 

Pattern:

It is created primarily by contrasting coloured streaks. Highlighted by the paratracheal parenchyma, they are visible as white dots on the cross-section of the vessel. The paratracheal parenchyma most often takes the form of winged to winged and streaked (occasionally in the form of thin rings surrounding the vessels). In addition to this form of axial parenchyma, zebrano has diffuse extravascular parenchyma – in the form of short, tangential groupings and ribbon parenchyma – in the form of continuous narrow strands arranged tangentially, often merging with the winged parenchyma. The very narrow and undersized medullary rays can only be seen "with the naked eye" on a radial section. These are homocellular rays. On the same cross-section, a striped fibre twist can be seen.

Typical defects:

Blistering, frequent cracking, fibre twist, mineral inclusions.

Properties of Zebrano wood:

According to the density scale, it is heavy wood (class II). The wood is characterised by a fibre saturation point moisture content of 30%, typical of domestic wood types. According to Monnin's classification, zebrano belongs to the medium shrinkage wood category – volume shrinkage averages 12.3-14.8%. The mechanical properties of this wood depend mainly on its density. Zebrano, compared to domestic timber of similar density, achieves a similar compressive strength along the fibres, averaging 62 MPa. Unfortunately, due to the frequent presence of strip twisting of the fibres, the average bending strength (around 95 MPa) and especially the tensile strength along the fibres (around 86 MPa) are slightly lower.

Similar species:

In terms of mechanical and physical properties, zebrano is compared to African amazaque wood.

Drying:

Slow due to significant density. If it dries too much, there is a high risk of deformation and cracking (mainly of the face). 

Working:

Easy, both by hand and by machine, but requires the use of well-prepared tools with increased hardness. This is due to the presence of hard mineral inclusions in the wood and the arrangement of alternately deflected fibres, which tend to pull out. Wood dust can cause irritation to the skin and eyes, so be sure to properly ventilate and dust off the workplace. 

Joining:

With nails and screws, it gives good results provided that it is pre-drilled. The alternative is bonding, which gives strong connections.  

Finishing:

Sanding and polishing produce good quality, smooth surfaces. Zebrano wood accepts paint and varnish well, which helps to enhance its aesthetic qualities.

Intended use:

Applications – furniture, veneer, joinery, interior fittings

Availability

52 mm – KD – SE edged – FAS grade

• Mechanical properties: There is a high risk of cracking. Bonding is good, nailing requires pre-drilling, working is good. Zebrano has good compressive strength and high impact strength.
• Modulus of elasticity: 17.5 GPa
• Tangential shrinkage: 11.0%
• Radial shrinkage: 8.8%
• Specific gravity: 790 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: not recommended contact with soil, medium resistance to external conditions, possible contact with high humidity