General Informations
Ochroma pyramidale is a flowering plant in the mallow family Malvaceae, commonly known as the balsa tree. It is a large, fast-growing tree that can grow up to 30 m tall. Balsa wood is a very light weight material with many uses. Balsa trees are native to Mexico, Central America and South America.
Because it is low in density but high in strength, balsa is a very popular material for light, stiff structures in model bridge tests, model buildings, and construction of model aircraft; all grades are usable for airworthy control line and radio-controlled aircraft varieties of the aeromodeling sports, with the lightest “contest grades” especially valuable for free-flight model aircraft. However, it also is valued as a component of full-sized light wooden aeroplanes, most notably the World War II de Havilland Mosquito.
Balsa is used to make wooden crankbaits for fishing, especially Rapala lures.
Balsa lumber is very soft and light, with a coarse, open grain. The density of dry balsa wood ranges from 40–340 kg/m3, with a typical density around 160 kg/m3. The wood of the living tree has large cells that are filled with water. This gives the wood a spongy texture. It also makes the wood of the living tree not much lighter than water and barely able to float. For commercial production, the wood is kiln-dried for about two weeks, leaving the cells hollow and empty. The large volume-to-surface ratio of the resulting thin-walled, empty cells gives the dried wood a large strength-to-weight ratio because the cells are mostly air. Unlike naturally rotted wood, which soon disintegrates in the rainforests where balsa trees grow, the cell walls of kiln-seasoned balsa wood retain their strong structure of cellulose and lignin
