Balsa wood is the lightest wood in the world, more precisely the lightest commercial wood. Botany mentions 2-3 species even lighter than balsa, but they are not used because they have no strength. Almost all sources give it as having the best strength to density ratio. But there are also sources that say it is much better in paulownia wood. It grows naturally in the rainforests of Central and South America, but does not form forests. That's why it was hard to find until recently, when it was acclimatized in countries in central Africa and southeast Asia, where it grows in plantations. Its uses have evolved steadily, from the structure of World War II fighter planes to the propellers of today's wind turbines.
From World War II's Mosquito to the Chevrolet Corvette
Balsa wood is known all over the world because it is very light. That's why when the British decided to build a lightweight fighter plane, they thought of it. The Mosquito, built by the British company de Havilland Aircraft Factory, it had much of its structure in balsa wood. It was a fighter-bomber that first flew in 1940 and was also used for reconnaissance and transport flights.
Another important event to which balsa wood contributed was the expedition of Norwegian ethnographer Thor Heyerdahl. He crossed the Pacific Ocean in 1947 on a raft made from balsa logs, proving that the ancient peoples of South America could reach Polynesia. He and his crew traveled 8000km, finally reaching the Tuamotu Islands in the Polynesian archipelago.
More recently, between 1997 and 2013, balsa wood was used to floor the Chevrolet Corvette sports car. The wood was sandwiched between two sheets of carbon fiber-reinforced plastic. The result was a much lighter car with the same level of strength and safety.
A fast-growing tree native to humid rainforests of the American tropics
Balsa, Pyramidal chroma in Latin, belongs to the Malvaceae. It is an evergreen evergreen in very wet areas and deciduous where there is a dry season. It grows naturally in the rainforests of Central and northern South America. It has been acclimatized in Africa and Asia, in countries such as Ecuador, Papua New Guinea, Thailand, Indonesia, Vietnam.
It thrives well in warm areas with plenty of rainfall and good drainage, especially on higher ground. It is very fast growing, growing up to 5m in a year. In 6-10 years it reaches 20-25 m in height and over 55 cm in diameter and can be pruned. It is short-lived, around 35 years. If it is not cut in time, it starts to deposit very hard wood on the outside and the inside begins to rot. It can no longer support itself, falls and rots quickly in the damp forest environment.
The mature tree can reach 40 m in height and 1-1.5 m in diameter. The trunk is covered with smooth whitish gray bark. The leaves are lobed and very large when the plant is small, reaching up to 1 meter and becoming smaller as the tree grows (30-40 cm). Flowers appear in the third year of life, at the end of the rainy season. The large inflorescences open late afternoon and remain open overnight. The fruits are green, in the form of capsules enclosing seeds surrounded by cotton threads that help them float away.
Farmers consider balsa an invasive species, a weed, because the wind-blown seeds drift onto their land and grow rapidly, disturbing crops. But it's called the forest's assistant because seeds that can't find a place to grow remain dormant and germinate after a forest fire or storm knocks down trees and leaves bare spots. The large leaves develop quickly and thus protect other species from the tropical sun. In the forest, balsa trees are rare, 2-3 trees per ha, but in plantations they can reach 1000 trees per hectare.
Properties, characteristics
The heartwood of balsa has a very light reddish-brown color, but it is very rare. The majority of commercially available wood is white. It is very light in color, ranging from very light yellowish-white to slightly white-brown with slight pink tints. The grain is straight with medium to coarse texture and low natural gloss.
Being a tropical wood, it has no annual rings but seasonal, but not visible, growth rings. The pores are large, with no specific arrangement and may be solitary, clustered or radially arranged. The medullary rays are visible to the naked eye.
The average density of anhydrous balsa wood is 160 kg/m³. Janka's hardness is also very low - the lowest of the commercial species - averaging 300 N. It generally works well, but surfaces that are slippery due to low density can be a problem if tools are not very sharp. Very easy to carve. Alburnum being the commercially marketed one is not rot resistant and is easily attacked by insects.
It is recommended to join the balsa elements with glue, not with screws or nails because they tear easily. When staining, great care should be taken as it tends to absorb a lot of color and thus stain. Consumption of finishing materials is high because, at least in the first coats, absorption is very high.
Why it's so easy
The name itself suggests it's a lightweight material. Balsa means cork in Spanish, meaning that craft that floats on water. The explanation for the very low density is the low lignin content - less than 40% - and the large wood cells with very thin walls. The ratio of solid balsa wood material to empty space is very small. To have the ability to stand up to such a small amount of woody material, very little lignin supported that sudează Between the fibers, the vessels of the balsa tree are very full of water and thus become rigid. The weight of water in the tree is 5 times the weight of the wood.
The high water content makes it compulsory to dry the wood in kilns immediately after felling. Wood cannot be sold wet because it would rot very quickly. Drying takes up to two weeks, during which time the wood reaches 6% moisture content and the micro-organisms inside are destroyed.
Uses
In the past, it was used to make gliders and airplanes because it was lightweight. Balsa was used to make life jackets, fishing gear and other objects that had to float. Over time, lightweight and strong synthetics emerged and replaced it in many areas. It is now used to make composite materials, contributing to their low final weight. It is thus replacing more expensive and harder-to-obtain synthetics, its rapid growth making it affordable. It is now used to make wind turbine propellers, surfboards and components for lightweight boats.
Being very lightweight, it is used for modeling bridges and buildings. Hobbyists use it to build model airplanes. Balsa is also used to make packaging and transportation boxes, musical instruments, picture frames, photo frames, platters and decorative objects. One interesting field is the movie industry. All the tables and chairs the protagonists fight with and which break easily are made of balsa wood.
Having so many air-filled cavities is also a very good insulating material. Many refrigerators and cold rooms have composite insulation materials containing balsa wood. It is also used to make sound insulation panels. In addition to air-filled voids, its low humidity also makes it a good electrical insulator.
There's a lot of talk about it being a very strong wood compared to its density. Some say that the strength to density ratio is better than oak and give it as the wood with the best such ratio. But they are contradicted by advocates of paulownia, who say that paulownia is a much better alternative because it is cheaper and stronger. In addition, it is rot-proof and absorbs less epoxy resin for stabilization than balsa wood. For the time being, both species are intensively cultivated and are an alternative solution for many areas, which reduces the pressure on logging.
I hope you find the above information interesting. As always, additions are welcome. And if you have any questions or queries, please leave them below in the space provided. I will be sure to reply.
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