Family: Bombacaceae, the bombax family.
Origin: West Indies, Central and tropical South America, Ecuador, India, Indonesia and the Caribbean.
Other common names: Corkwood, Guano, Lanero, Corcho, Enea, Lana, Pau de Balsa, Polka, Top, Tami.
The tree: The average height of the tree is 60 to 70 feet. It has large 12–20 in. weakly palmately lobed leaves. Balsa, with its large broad leaves is classified as a hardwood despite being the softest commercial hardwood. The trees are usually harvested after 6 to 10 years of growth. The name Balsa comes from the Spanish word for “raft.”
Appearance: Most of the balsa that is sold is the sapwood, which is white, off white and oatmeal colored, sometimes with a light yellow or pink cast and usually straight grained. It is very soft and spongy. The heartwood is a pale brown.
Density: Average reported specific gravity (ovendry weight/green volume) ranges from .10 to .17, equal to an air dry weight of 7 to 12 pcf. and up to 20 pcf. when seasoned. Janka hardness is 88 pounds of force.
Drying & shrinkage: Balsa must be dried soon after it is felled to avoid fungal discoloration and decay. Kiln drying over air drying is recommended to protect from splitting, warping and blue stain. Average reported shrinkage values (green to ovendry) 3% radial, 7.6% tangential and 10.8% volumetric.
Working properties: Balsa is an easy-to-work-with wood, provided sharp hand or power tools are used. It has a very slight blunting effect. It will take nails and screws easily, but rarely hold because of the wood’s softness, so glue is far more effective. Balsa stains and finishes easily, but will absorb much of what is applied. It is very easy to carve and is probably the easiest wood to shape and sand.
Durability: Balsa is very perishable and susceptible to termites and borers but can be treated with preservatives.
Uses: Balsa has a long, proud history. It was used in construction of the allied planes in WWll, and is one of the most frequently imported woods to the U.S.A. In WWl, balsa was used extensively in making life rafts and for packing armor plates for battleships. Because of its light weight and good insulating properties, it is still used as a packing material for high end products. It is generally the preferred wood for model making especially model planes.
Availability: Due to its rapid growth and expansive natural range, balsa is plentiful and will probably remain so. Also, it is now plantation grown, which increases the productivity.