Bangkirai Wood

The main country origins of Bangkirai wood (Shorea, spp.): Indonesia, Malaysia, Sri Lanka, Burma.

Bangkirai wood represents very resistant, hard and long lasting wood, immune to fungi and mould, and they do not penetrate inside due to high density of Bangkirai (Yellow Balau) wood. It is a tropical core wood of grey-brown to reddish-brown colour. The variable rotary growth is characteristic for bangkirai wood. The surface may show small apertures caused by insect living only in live wood, small pitch pockets and minor cracks. However, these occurrences do not have any effects on the wood characteristics. Growth rings are not noticeable, dry Bangkirai wood is odour-free. During the first months, tannin contained in Bangkirai balau wood can be washed out e.g. during rain, and cause stains to the plaster, stone, and constructions.

If we leave Bangkirai wood without maintenance, it will gain beautiful grey-silver colour in time. This can be prevented by means of a suitable paint finish such as Bangkirai oil of Osmo Color series. Pay attention to contact with metals, always use stainless screws for fitting, otherwise distinctive stains difficult to remove may occur on wood.

SCIENTIFIC INFORMATION BOTANICAL NAME: Shorea laevis Ridl. (Syn.  S. laevifolia Endert), Dipterocarpeceae family. LOCAL NAMES Bangkirai, Yellow Balau, Balau Kuning, Selangan batu, Anggelam, balau kumus, selangan batu kumus, thakian-samphon, mikai, selangan kumus, kumus, penapak, benuas, bangkirai, balau tanduk, chan OTHER NAMES Bangkirai, Yellow Balau (UK, USA, Fr, Sp, It, Sw.  NI, Gm). Yellow Balau is usually used in Malaysia and Bangkirai is usually used in Indonesia. EOGRAPHICAL DISTRIBUTION All over Kalimantan, Indonesia HABITUS The tree height may reach 50 m, the length of the clear bole is 35 to 40 m, the diameter is 100 cm and over.  The buttress is as high as 2 m. The outer bark is grey, red or brown, sometimes even dark red with grooves and peels off in small thin pieces.  The bark contains dark yellow resin. GENERAL CHARACTERISTICS Colour: The Heartwood is brownish yellow, the sapwood yellowish pale light brown. Texture: Wood texture ranges from fine to rather coarse Grain: The grain is straight or interlocked. Touch: The wood surface is smooth or alternately smooth and rough owing to the interlocked grain. Gloss: The wood surface is glossy. Figures: The radial section shows stripes in a lighter colour. STRUCTURE Vessels: Most vessels are solitary.  A small part of them are in groups of 2 to 4 in radial direction, sometimes in tangential and oblique lines.  They are round or oval, have a diameter of 1 00 to 300 ?? a frequency of 2 to 10 per Sq mm , and contain much tylosis.  The perforation plates are simple. Parenchyma: The parenchyma are of the paratracheal type in the form of complete or incomplete borders to the vessels.  There are also apotracheal parenohyma in the form of short, tangential bands besides diffuse parenchyma. Rays: The rays are homogenous, fine and short, and have a frequency of 6 to 8 per mm.  They sometimes contain a brown deposit. Intercellular canals: The Intercellular canals are almost always smaller than vessels, occasionally of the same size.  They are arranged in long series, and contain white resin. Fiber: The fiber are 1,203  long with a diameter of 19.9 ; wall thickness of 1.9 and lumen diameter of 16.1. PHYSICAL PROPERTIES Specific gravity: 0.91 (0.60 - 1.16) g/cm3  Strength class: I ? II Shrinkage: Shrinkage to oven-dry condition is 4.5 % ( R ) and 8.3 % ( T ) Fibre Saturation Point: 23 % MECHANICAL PROPERTIES Bending strength 150 mPa 21756 psi Modulus of elasticity 22940 mPa 3327 1000psi Crushing strength 85 mPa 12328 psi JANKA Hardness 7.99 Kn 1798 lbs force Note: at 12% moisture content CHEMICAL PROPERTIES Content Cellulose 62.9 % Lignin 24.0 % Pentosan 16.8 % Ash 1.0 % Silica 0.4 % Solubility Alcohol ? benzene 3.0 % Cold water 0.8 % Hot water 2.6 % 1 % NaOH 10.9 % DURABILITY AND TREATABILITY Durability: Fungi - Class 2 - Durable Dry Wood Borers - Heartwood durable Termites - Class D - Durable Treatability: Bangkirai wood is difficult to treat. DRYING 2.5 cm and 4 cm thick Bangkirai boards are kiln dried from 50% to 15% in respectively 6 and 9 days in a drying temperature of 43 degrees Centigrade to 71 degrees Centigrade and a relative humidity of 84% to 38%. Bangkirai wood is difficult to dry as it easily splits, checks, and deforms.   WORKING PROPERTIES Despite its hardness, bangkirai is not so difficult to work, e.g., with hardened tipped saws or it can be planed smoothly with small cutting angle. Holes should be drilled before nailing to prevent splitting. COMMON USES Due to its high strength and durability,- bangkirai wood is used for heavy construction under roof as well as in the open, such as bridges, railway sleepers, electric poles, flooring, marine construction, boat building, vehicular bodywork and housing.