Balsa WoodWhere do you find balsa wood?

Balsa trees grow in the rain forests of Central and South America. Its range extends south from Guatemala, through Central America, to the north and west coast of South America as far as Bolivia. The country of Ecquador on the western coast of South America, is the primary source of model aircraft grade blasa. Blasa needs warm climate with rainfall and good drainage. The best of balsa is usually found on the higher ground. Ecquador has the ideal geography and climate for growing balsa trees. The scientific name for balsa is ochroma lagopus. The word balsa is Spanish meaning raft, for its excellent floatation qualities. In Ecquador it is known as Boya, meaning buoy.

How does balsa grow?

They grow by themselves or in very small, scattered groups. For hundreds of years now, balsa was considered a weed tree. They reproduce by growing hundreds and hundreds of long seed pods, which open and, from the wind, scatter the new seeds over large areas of the jungle. Then one day sun light peaks in a opening through the trees large enough for the sun to strike the and start the seeds growing. Balsa will grow up as thick as grass. When they mature, there may be only one or two balsa trees to a large area of the jungle.

How long does it take a balsa tree to grow?

Balsa grows very quickly like weeds.  Six  or seven months after germination, the tree is about 1 inch in diameter and 12 feet tall. It take about 6 to 10 years before the tree is ready for cutting. By this time the tree has reached a height up to 90 feet tall and a diameter can be 45 inches. The balsa leafs are similar to a grape leaf, only a lot larger.

All three types of balsa grain

In selecting balsa for your model, it is important the way the grain runs through the wood as well as the weight of the wood. The grains direction controls the sturdiness or flexibility of balsa wood more than the density does. If the wood is cut from the tree so that the annular rings run across the thickness of the wood, then the wood will be basically flexible from side to side. After soaking balsa sheets in water some sheets can be rolled into a tube shape without breaking. If the sheet was cut with the annular rings going through the thickness of the wood (C-grain, quarter grain), the wood will be very stiff side to side and cannot be bent without cracking. If the grains direction is less defined (B-grain, random cut), the wood will have properties between A and C grain. B-grain is the most common and is great for most jobs. Understand that whenever you come across pure A-grain or C-grain sheet learn where to use them to take best advantage of their characteristics.

A-grain is good for flexing the width of a balsa sheet.  It is used for bending around objects or wings on airplanes.  Half of all balsa grain sheets end up as B-grain which is an all-purpose balsa item.  C-grain is good for ultra-light airplanes that need to have stiff wings and are not flexed so C-grain allows the wings to keep their shape and be very light. Please note that C-grain is brittle and if flexed it will shatter easily.

Why is balsa wood so light?

Why is balsa wood so light? Unlike other hardwoods, balsa wood cells are fatter and contain more water. Only 40 percent of the wood is actually solid because it contains less lignin – the plant “cement” that solidifies wood. It is considered the lightest and softest of the hardwoods. Because of this nature, green balsa wood has to be slowly kiln-dried.

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