How hard is balsa wood

The softest wood in the world

The term softwood basically stands for a classification of certain types of wood into a botanical category. The name originally comes from customs. By softwoods are meant types of wood whose density falls below a value of 0.55 g / cm³. This applies, for example, to native conifers such as spruce and pine as well as to deciduous trees such as linden and poplar. Balsa wood, the softest wood in the world, only grows in the tropics.

By Marco Schmidt - Own work, CC BY-SA 2.5

Balsa wood: the lightweight among the types of wood

The balsa tree is a tropical plant that is grown on all continents. The trees are extremely fast-growing and reach heights of 30 to 45 meters. The trunk has a smooth bark, which is usually light gray and may have a white marbling. With a density of 0.1 to 0.2 g / cm³, balsa is the softest wood in the world. PS rigid foam, which is used, among other things, as foam plastic Styrofoam, has a similarly low density. The density of balsa wood varies depending on the cut. Thin branches are the softest, while wood from the middle of the trunk has a higher density and strength.

Areas of application for balsa wood

Balsa wood is not only the softest wood in the world, it is also extremely light. For this reason, it is widely used to build rafts in the tropical regions of the world. Model builders also love the soft natural material. Balsa wood is used in the construction of aircraft and ship models and is used for the design of model railways. It is just as easy to process as cork. In the business sector, Balsa is used, among other things, to build rotor blades for wind turbines. The extremely light wood was also used in the leisure sector. In the Hawaiian Islands, balsa was used to make surfboards. However, this happened before the first synthetic resin models hit the market.

Balsa wood made history as a building material for the Kon-Tiki raft, with which the Norwegian Thor Heyerdahl sailed across the Pacific in 1947. The adventurer started in the Peruvian port city of Callao and ran aground on a reef less than five months later in the Tuamotu archipelago. The raft consisted of nine trunks of balsa wood, which were connected with 5.50 m long cross trunks made of the same material. The substructure, the mast and the deck were held together exclusively with hemp ropes and traditional materials. Nails, screws or other metal components were not used.

While particularly hard types of wood such as teak were used in shipbuilding for reasons of resilience, the Norwegian used the great buoyancy and low weight of balsa wood to construct a buoyant watercraft.

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