Introduction |
The Standard Malaysian Name for the heavy, yellow to
brown timbers of the genus Shorea (Dipterocarpaceae). Vernacular names
applied include balau (Peninsular Malaysia) with various epithets,
selangan batu No. 1 (Sabah), selangan batu (Sabah and Sarawak) and other
localised names too numerous to be listed here. Major species include
S. atrinervosa, S. foxworthyi, S. glauca, S. laevis, S. materialis, S.
maxwelliana, S. submontana and S. sumatrana. The sapwood is lighter in
colour and is sharply defined from the heartwood, which is yellow or
grey-brown and darkens to deep brown on exposure. Also known as
Selangan batu (Brunnei); Phchok (Cambodia); Sal (India); Anggelam,
Balau, Bangkirai and Dammar laut (Indonesia); Mai chik khok (Laos);
Thitya (Myanmar); Gisok, Malayakal and Yakal (Philippines); and Aek, Ak,
Balao, Takhian-samphon, Teng and Rang (Thailand). |
Botanical Name |
Shorea principally S. kunstleri, S. guiso, S. collina, S. ochrophloia. Family: Dipterocarpaceae. |
Natural Durability |
The heartwood of this timber is naturally durable, but
the sapwood is liable to fungal infestation. Under graveyard testing,
untreated specimens (50 mm x 50 mm x 600 mm) of balau kumus hitam (S.
maxwelliana) gave a life-span of 15.8 years, which made it one of the
most durable timber tested in Peninsular Malaysia (Jackson, 1965). Other
test results recorded by Jackson include S. laevis (8 years) and S.
glauca (7 years). In a later series of tests, Dahlan & Tam (in
press) reported that S. laevis lasted 7.4 years, thus confirming the
results obtained by Jackson. Balau is thus placed in the durable class
with some species classified as extremely durable. Treated specimens of
balau laut (50 mm x 50 mm x 600 mm) gave an average service life of 11
years. Untreated railway sleepers (125 mm x 237 mm x 1,950 mm) of balau
kumus and balau laut lasted a minimum of 15 years and 11 years
respectively. |
Uses |
The timber is suitable for all forms of heavy
construction, marine construction, ship and boat building (keels,
keelsons and framework), piling, beams, columns (heavy duty), bridges,
wharves, cooling tower (structural member), railway sleepers, vehicle
bodies (framework and floor boards), boat building, plywood, joinery,
cabinet making, mallets, fender supports, door and window frames,
staircase (carriage, newel and stringer), pallets (heavy and permanent
type), tool handles (impact), telegraphic and power transmission posts
and cross arms, posts, joists, rafters, flooring (heavy traffic),
decking and heavy duty furniture. |
Texture |
Texture is fine and even, with deeply interlocked grain. |
Density |
The timber is a Heavy Hardwood with a density of 850-1,155 kg/m3 air dry. |
Shrinkage |
The timber falls into Strength Group A (Engku, 1988b) or SG 1 (MS 544:Part 2:2001). |
Defect |
The heartwood is very seldom attacked by boring
insects, but the sapwood, however, is liable to infestation by
powder-post beetles. Spongy heart and compression failures are unusual
except in large, somewhat overmature trees (Thomas, 1958). Occasionally,
resin pockets filled with solidified resin may be found. A tangential
zone of abnormal tissue with abundant intercellular canals and extending
longitudinally for considerable distances may also be found. |