Trees are a fundamental part of our ecosystem, and there are an estimated 73,000 different tree species on Earth. Different trees have different kinds of wood suitable for various uses depending on their characteristics, qualities, and hardness. So what is the hardest wood in the world? Particular tree types with needle-like leaves such as cedar, cypress, pine, and hemlock produce what we call “softwood.” Meanwhile, broad-leafed trees like oak, sycamore, maple, and alder are the source of “hardwood” lumber.
Although you may argue that all wood is indeed hard, there are specific kinds that can dull your tools faster than others. Some types of wood can even rival the hardness of steel and other metals. But how do you measure and classify a tree’s hardness? What is the basis used in order to say that a wood is one of the hardest in the world?
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How is wood hardness measured?
The standard test to measure wood hardness is called the “Janka hardness test,” named after its creator, an Austrian-born American wood researcher named Gabriel Janka.
You’ll need a steel ball precisely 0.44 inches in diameter, with a belt horizontally attached around the ball’s middle. Meanwhile, your sample wood, measuring two inches thick, two inches wide, and six inches long, should have a moisture content of precisely 12 percent and be clear of any knots.
To conduct the test, you take the ball and press it into the wood until half of it (up to the belt) is successfully pressed in. The wood’s Janka score is the amount of force it took for the steel ball to reach that depth in the wood. The higher the score, measured in pounds-force (lbf), the harder the wood.
What is the Janka scale?
The Janka test is used to quantify the hardness of wood. The Janka scale is the standard assessment for hardness, as it tests the wood’s density. The denser the wood, the more force it takes to press the metal ball into it. This determines how “hard” a type of timber is. However, the hardness measured by the metal ball and defined by the Janka scale doss not equal the overall strength of the wood. It’s a specific attribute that means “resistance to indentation.”
If a type of wood scores high on the Janka scale, it does not directly indicate that it is super-strong and resistant to all destructive forces. After all, different wood types have different strengths and weaknesses. It does, however, mean that the wood needs a greater force to act on it in order to make a dent.
According to Eric Mier, founder of the Wood Database and author of WOOD! Identifying and Using Hundreds of Woods Worldwide, the Janka test for hardness is ideal for timber used as flooring. Harder wood is more durable against scratching, denting, and day-to-day wear and tear.
Top 10 trees with the hardest wood in the world
Most hardwood used for cabinetry, home construction, and similar projects has a reliable hardness that can last for many years. However, they may not compare to the timber Mier’s Wood Database lists as the world’s 10 hardest woods.
Literally meaning “ax breaker” from the Spanish words “quebrar hacha, this type of wood scores 4,570 lbf on the Janka scale.
2. Lignum vitae
A South American and Caribbean hardwood with a 4,390 lbf score on the Janka scale.
This tree endemic to Australia scores a whopping 4,270 lbf on the Janka test.
The snakewood is on the Janka scale at 3,800 lbf. It’s also one of the most expensive types of wood because of its unique, snake-like patterns.
At 3,710 lbf on the Janka scale, this tree also comes from the genus Lignum vitae. Found in Central and Northern South America.
As its name suggests, this African hardwood is protected by large, sharp thorns. It scores 3,680 lbf on the test.
7. African blackwood
This decay-resistant wood is often completely black, sometimes referred to as “true ebony.” Its Janka score is 3,670 lbf.
8. Black Ironwood
Black Ironwood scores 3,660 lbf and is one of the heaviest types of timber in the United States. It is typically found in South Florida.
9. Katalox / Wamara
Scoring 3,655 lbf on the Janka test, the Katalox wood is great for cabinetry and a good substitute for ebony.
Also known as Curupay. It has a Janka hardness of 3,630 lbf and is found in Argentina, Paraguay, and Brazil.