why is balsa wood so light?


Balsa wood is a lightweight

One of the interesting kinds of wood is balsa wood. It’s so lightweight, and the structure also feels close to soft- tends to get scratches easily, you can probably scratch its top surface by pressing nails. Even though, its genesis comes from hardwoods.

Reasons why balsa wood is so lightweight?

  • Low density– With a density of 0.1 to 0.2 g / cm³, balsa is the softest wood in the world.
  • Long cells– Its cells are bigger than many kinds of wood- A reason to be counted for why its mass/volume ratio is low. 
  • Fast-growing It can grow more than 5 meters (16.5 feet) per year in full sun, reaching a maximum height of about 30 meters (100 feet). 
  • Contains more water– Its cells contain about 40 percent of water, which gets extracted in the process of drying wood in the factories, making it even lightweight.
  • Walled cells– Balsa wood’s cells are covered with a shell, almost filled with air.
  • Contain less amount of lignin- Balsa trees have less amount of lignin. 

Lignin is found in all woods, constituting around %10-30of the dry mass of wood, giving trees their rigidity and making them water-resistant and resistant to degradation.

It’ has least density.

Despite the fact, balsa wood is hardwood. Unlike other hardwood trees, its trees grow faster- a reason for their low density and big cells, containing only %40-50 of solid substance, and the rest of %60 is filled with air. Its density is lower than water. This is why tropical regions use balsa wood for building rafts quite often.

It’s soft to touch.

Speaking of its reliability, although it’s soft by nature and in fact, the sheer-strenth is very low. But it’s quite a useful species of woods. Used in making boats, crafting, wood arts, surfboards, etc. Unlike other woods with a light density, this wood was strong and was once used to make airplanes. Ecuador is the native land of balsa trees.

So, if you want to know why is the balsa wood so soft and lightweight. Read on to get your answers. 

Related: Balsa wood properties: Is Balsa Wood Strong? Why not?

About balsa wood weight and structure.

  • Large cells with very thin walls allow balsa wood to have a small ratio between solid matter and open space. 

Unlike other hardwoods or softwoods for example oak, walnut, etc. A substance known as lignin is available- acts as organic glue to combine cells of wood together.

  • Based on a study, balsa has the minimum amount of this substance, thus cells of balsa wood move freely in a space filled with air.

Growth rate

People who are into woodworking may already know that hardwoods trees take quite a long to grow. However, that’s not the case with balsa wood. As its trees are one of the fast-growing trees in the world. 

Compressed (klin dried)

  • Lastly, the weight of balsa wood is actually compressed to turn it lower. With this being said, green balsa wood ( a freshly cut wood) typically has 5 times more weight than what we use as lumber.

But green woods are not viable to be used. Every wood gets to go through a process known as kiln-dried- in which all the impurities, water, dust, etc, get extracted. It helps kill bacteria, fungi, and clean compounds that can damage or can cause issues in the long run.

What wood is similar to balsa?

  • Albezia wood may be considered an alternative to balsa wood because it is strong and has almost a similar density.

However, unlike balsa wood, the tree does not grow all over the world instead it is found only in some specific tropical regions.

Industrial uses of lightweight woods

Definitely, light woods such as balsa wood cannot be used to craft furniture due to low shear strength. Neither such woods make any sense using them in the construction for decking or using beams.

Despite that, they still got many uses around the globe. Mostly are related to crafting boats, surfboards, etc because these can not sink in the water.

Some uses of lightwoods are as follows.

  • In the tropical regions of the world, lightweight woods are high in demand for the construction of rafts, boats, and their parts. Particularly, balsa wood which is the strongest yet lightest wood- an ideal choice for building boats.
  • Wood artists use lightweight woods as crafting such woods is quite an easy job.
  • Modelers use balsa wood to design and construct aircraft and ship models, and they also use it to build model railways.
  • One of the uses of balsa in the business sector is to construct rotor blades for wind turbines.
  • Historically, balsa wood was used for making surfboards in Hawaii. 
  • Firestarters or paper making are also some common uses of such trees.

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