Bangkirai

Bangkirai (Shorea laevis)

shorea, balau, teck de borneo, chan, thity, kedawang

Origin:

Trees of the genus Shorea are found in south-east Asia. They grow naturally in the rainforests of Thailand, Laos, Vietnam, Cambodia, India, Pakistan and Indonesia and Malaysia. They are an important component of forest communities in the above-mentioned countries

Tree habit:

Light Bangkirai are trees that can reach heights of up to 50 m and diameters of about 1.2 m. The trunk is covered with cracked, grey-brown bark peeling off in patches, reinforced by board-like flutes reaching several metres high from its base.

Structure type:

Diffuse-vascular; large vessels mainly distributed in clusters (2-3 each; within the clusters the vessels are arranged radially), visible to the naked eye (0.11 to 0.23 mm in diameter). There are an average of 3 to 6 vessels per 1 mm² of cross-section. 

Sapwood:

Narrow (2 to 8 cm wide), light grey to light yellowish grey in colour

Heartwood:

In freshly sawn wood, heartwood is coloured yellow-brown. When exposed to light and the oxygen in the air, heartwood darkens rapidly and intensely, becoming dark brown.

Fragrance:

Fresh wood gives off an aroma similar to nutmeg. 

Pattern:

Light Bangkirai contains gum-resin ducts filled with a translucent, pale-yellow resin (damara) that seeps out of the wood when exposed to heat. These ducts are found in tangentially running strands of banded (ribbon) parenchyma, often connecting to paratracheal parenchyma found in the vicinity of the vessels. The paratracheal parenchyma can occur as perivascular, winged, winged-streaked or unilateral. The wood also contains diffuse apotracheal parenchyma. Annual increments are barely visible and only on the cross section. Fine medullary rays are virtually imperceptible. An irregular fibre twist is quite often present in the wood, best visible on radial section. 

Typical defects:

gum-resin leaks, fibre twist.

Properties of Bangkirai wood:

According to a six-grade scale, it is very heavy wood (Class I). The average air-dry density (wood with a moisture content of about 12%) is 900 kg m³. The wood described is characterised by a low fibre saturation point moisture content (about 23%) and high shrinkage values. According to the classification, light Bangkirai belongs to medium shrinkage wood. The high density of the wood is associated with very good strength properties. For example, the average compressive strength along the fibres is 80 MPa and the tangential crushing strength is 125 to 150 MPa. Similarly, the modulus of elasticity is at a high level (range 12.6 to 20 GPa).  

Similar species:

Visually: other types of Asian wood, for example Keruing, while in appearance and properties terms: Cumaru, Dabena, Garapa wood.  

Drying:

Drying is difficult and slow, with a tendency towards cracking and desorption deformation.

Working:

Working is not problematic, but due to its high density and the presence of an intricate fibre system, it requires the use of suitable tools (e.g. saws with carbide or ceramic abrasive pads). Nevertheless, smooth and glossy surfaces can already be achieved when planing, which is facilitated by the compact structure.

Joining:

Making joints with metal fasteners (nails and screws) requires pre-drilling due to the danger of cracks. It is best to use single-component polyurethane adhesives for adhesive joints.     

Finishing:

Generally accepts paints and varnishes well; gum-resin substances can be a hindrance. 

Intended use:

Light Bangkirai wood in the countries of harvest has quite a wide range of uses. The high natural durability of this material allows it to be used for external structures, including elements working in contact with water and soil (railway sleepers, bridge piles). It is also a boatbuilding wood used to make the sleepers of vessels. On land, it is often an industrial surface subject to heavy use (loading ramps, floors in wagons and containers). In Poland, light Bangkirai is available primarily in the form of various types of decking boards – one-side finely grooved and both-side grooved. The wood can also be used to make garden furniture.

We offer Bangkirai decking in the following profiles:
- 19x90 mm – one side finely grooved / other side smooth
- 21x120 mm – one side finely grooved / other side smooth
- 21x145 mm – one side finely grooved / other side smooth
- 21x145 mm – one side coarsely corrugated / other side smooth
- 25x145 mm – double-sided grooved – fine/coarse groove