BALSA WOOD

Because of balsa wood vulnerability to attack by insects and fungi, it is very important that the Balsa logs be taken out of the woods and delivered to the sawmill just as quickly as possible. Unlike the logging of other timbers, you cannot cut down a great number of logs and stack them for transportation while awaiting a propitious time. They must be taken out of the woods immediately, preferably the same day, and send to mill. At the sawmill we don't waste any time with them either. The rafts are broken up immediately arid the logs are dragged up a long ramp to the head saw, where they are squared.

From the head saw they go to a gang saw, which converts them into boards. Importance of Kiln Drying The next step is one of the most important in the process of manufacturing Balsa boards. It is kiln drying, by means of which the moisture is removed from the wood. Without kiln drying Balsa would not have its characteristic lightness, nor its strength. Kiln drying kills bacteria, fungi, and insects; because the wood is dry it prevents them from returning. Balsa that is not kiln dried, or improperly kiln dried, bears very little resemblance to the finished product which most of us know.

But kiln drying is a rather fine art. For the sake of economy, the wood should be dried as quickly as possible. but if it is dried too quickly, it may be irreparably damaged - slits appear in the wood, and the boards twist and warp. You may have a condition where the outside may be dry and the inside damp - this is knows as case hardening. When a case hardening board is cut, it will twist like a cork screw. Drying is accomplished by the application of heat through steam heat exchangers, and through the regulation of the amount of humidity. If the heat is held at too low a point, it may increase fungus attack instead of killing it. If the heat is too high, it will kill the natural elasticity of the wood.

If the humidity is too low, the wood will dry out too fast, and will result in all the drying defects mentioned before. If the humidity is held too high, the wood will not dry. The dry kiln operator then has to walk a tight rope between the two extremes, manipulating his valves and controls so that the fastest, most efficient drying is accomplished, with a minimum of damage. This is done by placing the Balsa lumber, stacked in layers, on cars with spacers between the layers, to permit the passage of air. The cars are placed in the kilns, which are long and tunnel-like insulated compartments where they are subjected to controlled heat, humidity and air circulation. After spending from ten days to two weeks in the kilns, the lumber is removed, cooled gradually and is then reworked to remove defects; it is planed to thickness and is then packed in bales for shipment via ocean steamer. It is sold to other manufacturers, who cut the wood into the many useful things, for which Balsa is so well suited.

Balsa (or balsa wood, whichever you prefer to call it), has been the standard material for model airframe construction since it first became available commercially in suitable cut sizes. Although, botanically at least, balsa is only about the fourth or fifth lightest wood in the world it is the first of all the woods which combine strength with lightness. On a strength/weight basis, in fact, balsa compares favorably with most other woods - even oak.

This is one of the main reasons why it is so suitable for aero modelling, where strength is required for minimum weight. Many other materials which are as light as, or lighter than balsa, also fall down on this question of combining strength with lightness and cannot be used in small sections - expanded polystyrene, for example. The other great advantage of balsa is the ease with which it can be cut or carved, and joined with quick drying cement. Having a fairly open structure, balsa cement impregnates and adheres strongly to balsa with the result that properly made glued joints are as strong or stronger than the wood itself.

With balsa readily available in a wide range of sheet, strip and block sizes, very few tools are required for working balsa either in solid form or for the assembly of built-up frames, etc. At the same time, however, there are disadvantages. The balsa tree is very fast growing, reaching a height of 15 feet of more within a year and growing to between 60 and 90 feet within the next six to ten years. After that time the tree begins to deteriorate and rot. As a result both the density and quality of the lumber obtained by felling balsa trees can vary enormously.

The result for our materials:

Made only with the best balsa wood available

Kiln-Dried to perfection; straight from the plantations to the kilns

Possess the correct density and the correct moisture content

Remarkable high physical properties

Contain no gaps and no soft corks

Contain no water hearts, no decay stains, no fungus and no insect attacks

Balsa Wood’s light weight makes it an ideal fit for this demanding application. Aero-modellers usually have strict requirements on density, and may wish to use our ‘competition selects’ service to ensure the pieces they order are right for their project.

Light Balsa at (6-10 pounds per cubic foot),

Medium Balsa at (10-14 pounds per cubic foot)

Heavy Balsa at (14-19 pounds per cubic foot) are all 40% extra

For more information or need price list please send email to us at info@karyadasarutama.com

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