Interesting Facts About Balsa Wood
Ochroma pyramidale--or balsa--colonizes disturbed and inhospitable ground in the American tropics. From southern Mexico through Central America and as far south as Bolivia in South America, balsa springs up wherever a hole in the forest canopy opens. The seeds, spreading on the wind like dandelions, need direct sunlight to germinate.
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Like Weeds
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Fast-growing balsa sprouts in newly opened clearings and grows as thickly as grass. Only the strongest survive long, and mature trees are scattered through the jungle and mixed with other species. In only six to 10 years, balsa trees will reach heights of 60 to 90 feet. Trees of that age have trunk diameters from 12 to 45 inches. The leaves on young trees may be 4 feet across, but decrease in size with the balsa's age. Mature trees have evergreen leaves only 8 to 10 inches wide.
Harvest
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Balsa's role as a fast-growing nurse tree for less hardy species of plants is short-lived. At maturity the trees put down a deep taproot, becoming extremely drought resistant as the porous heartwood fills with water. The trees rot slowly from the core outwards and typically die before they reach 100 years of age. The balsa tree first flowers at age 3, and the edible blooms feed many species of wild parrots and honeycreepers. Balsa tree are harvested for lumber after only six to 10 years of growth, before the water-storing habits ruin the commercial value of the wood.
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Flotation
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When dry, grades of balsa wood vary considerably in weight. The lightest weighs only 4 lbs. per cubic foot. Model airplane builders rate 6 lbs. per cubic foot or lighter as contest-grade balsa. The heavier balsa has more use where greater strength is needed. Only 40 percent of the volume of balsa is wood--air-filled empty cells takes up the rest.
Balsa was once important for airplane frames and flotation devices such as life vests. Large balsa plantations begun in WWII to supply military demands were never used. Aluminum and other modern materials took its place.
Surfboards
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Good flotation qualities and a high strength-to-weight ratio made balsa the favorite material of early surfers. The availability of cheap foamed plastic boards caused a quick decline in the balsa board market, although some traditionalists never gave them up completely. Now, because balsa is a renewable resource--and plastic foam has been criticized as harmful to the environment--balsa again is in vogue. Initially more expensive than foam, balsa boards aren't smashed by waves, and their long useful lifetime lets surfers recover the investment in only a few years.
Historical Facts
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The Incas used balsa wood rafts to transport armies across rivers--a sight that inspired the conquistadors to name the wood balsa, or raft. Surfboards used by Hawaiian royalty were carved from willi-willi, a local balsa with probable South American origins. In more recent times, Greg Noll at Waimea Bay and Phil Edwards at The Pipeline were the first to successfully ride those legendary waves. Both rode in on balsa surfboards.
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References
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- Photo Credit toryporter at Flickr.com
