Balsa

Balsa is the lightest and softest timber used commercially. It exhibits an unusually high degree of buoyancy and provides very efficient insulation against heat and sound. The wood can be adapted to a great number of special end-uses where these properties are essential. The timber is white to oatmeal in colour with sometimes a pinkish tinge near the hart. Still most commercial material is from the sapwood.  It has a coarse and even texture resulting from the large and infrequent sap conducting vessels. Straight grain. It is a short lived fast growing tree native to tropical South and Central America but it is widely cultivated in the tropics. Trees grow to 21m high and diameter of approximately 0.5m within seven years, reach maturity in 12-15 years after which they deteriorate with increases in density leading to the formation of hard and heavy wood and heartwood which tends to become waterlogged. Although when planted outside their natural range, the wood produced tends to be heavier and outside the commercially accepted density range for balsa the species has been planted successfully in Papua New Guinea, Malaysia, Fiji, and Indonesia. 

Characteristics of balsa wood make it a unique hardwood albeit, when weight for weight basis is excluded, it is the weakest of all commercial species. The logs must be converted promptly after felling to prevent extensive splitting. Kiln drying is preferred to air-drying due to low moisture movement and very high green moisture content (200-400%). The timber works well with tools but cutting edges must be sharp to avoid crumbling and to ensure a good finish in planning.  Material can be nailed, but its holding power is poor. Glues well, stains and polishes satisfactorily but it is very absorbent. Timber is prone to attack by Anobium, termites and longhorn beetle.  The sapwood is permeable, heartwood resistant to impregnation. Timber cut form old trees is often brittle and decayed. Traditional uses include: surf boards, laboratory mounting boards, fish net floats, aircraft construction and model making.