Being a hardwood that can be cut with a craft knife has made balsa the ultimate wood of empowerment and placed it at the heart of millions of children’s play factories. Balsa wood evokes many material memories, with its powdery white, lightweight warm surface which can be scored with a fingernail. It is recognized as the best material to work with simple tools, and has an informality and accessibility compared to some of the more noble woods such oak.
It is easy to forget that the physical properties and appearance of wood are dictated by the climatic conditions in those parts of the world in which it is grown. This richness of variation in growing environments gives it something like the qualities we associate with wine. Species like bamboo and balsa are the results of a rich and warm climate with plenty of rainfall and good drainage, which enables the trees to grow rapidly. It is this rapid growth that produces featherweight wood, which gives it the highest strength-to-weight ratio of any wood – although it is not technically the lightest wood in the world, as two or three other plants classified as wood, but not usable in the same way, are lighter.
Today, most commercial-grade balsa comes from Equador, which has the ideal geography and climate for growing the tree. The word balsa derives from the Spanish word for raft, reflecting its excellent buoyancy properties. In Ecuador, this quality is further reflected as the wood is known as Boya, which means buoy.
Image: Riley Classic balsa surfboard fin
Key features
•Very light: 40 kg/m3 (2½ lbs/ft3)
•Good shock and vibration absorption
•Can be easily glued and cut
•Poor steam bending
•Extremely easy to work
Sources
Central and South America, particularly Equador.
Sustainability issues
The speed of growth accounts for the lightness of this wood. It can grow up to 30 m (100 ft) in 10-15 years and as it’s so light it is easy to harvest and transport. Although wild balsa has gradually been disappearing, it has been successfully grown under plantation conditions.
Production
As every child who has ever played with balsa wood will know, it is very soft and can be cut with basic crafts tools. Its open structure also means that it absorbs stains very well, but it does soak up a lot of the stain.
Typical applications
Apart from model aircraft, it is also used for speed boats, heat, sound and vibration insulation, buoyancy in lifebelts and water sports equipment, theatre props, surfboards, and even as the skeleton for planes in World War II.
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–Very good strength-to-weight ratio –Extremely buoyant –Easy to work –Good shock absorbency –Sustainable |
–Poor steam bending –Extremely porous so tends to soak up stain |