'Balsa' (''Ochroma pyramidale'', synonym ''O. lagopus'') is a large, fast-growing
tree that can grow up to 30 m tall, native to
tropical South America north to southern
Mexico. It is
evergreen, or dry-season
deciduous if the dry season is long, with large (30–50 cm) weakly palmately lobed leaves. The name ''balsa'' derives from
Spanish for a
raft.
The
timber is very soft and light with a coarse open grain. The
density of dry balsa
wood ranges from 100–200 kg/m³, with a typical density of about 140 kg/m³ (about one third the density of other kinds of hard wood). This makes it a very popular material for
model building and buoyancy materials (lifebelts, etc.), and was famously used by
Thor Heyerdahl in his raft
Kon-Tiki. It is also a very popular material to use when making wooden
crankbaits for fishing, as it is low density but high in strength. Balsa wood is used to make very light, stiff structures in
model bridge tests and for the construction of light wooden
aeroplanes, most famously the
World War II de Havilland Mosquito. It also is used in the
floorpan of the
Chevrolet Corvette Z06 sandwiched between two sheets of carbon fibre. In table tennis blades, a balsa layer is typically sandwiched between two pieces of thin
plywood.
Despite being very soft, balsa is classified as a
hardwood, the softest commercial hardwood.
References
Technical Description, History, Facts, Specs
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Species description
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Germplasm Resources Information Network: ''Ochroma pyramidale''
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Photo of foliage and flower
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Kon-Tiki museum website
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Balsa rafting in Ecuador
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Table Tennis Balsa Blades