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What is the Janka Hardness Scale?

The Janka hardness scale (often referred to as the Janka hardness list) is an industry-wide measurement of the hardness of wood. The test measures the amount of force required to embed a .444-inch steel ball to half its diameter into a material. The more force required to embed the steel ball, the harder the material is.

For hardwood flooring, the test usually requires a 2" x 6" sample with a thickness of at least 6-8mm, and the most commonly used test is the ASTM D1037. When testing wood in lumber form the Janka test is always carried out on wood from the trunk of the tree (known as the heartwood) and the standard sample (according to ASTM D143) is at 12% moisture content and clear of knots.

The Janka score not only provides an indicator of how hard and durable material is but also how hard it is to saw, mill and nail. In the image below featuring different types of wood, you can see that the Kurupayra Hardwood is at the top of the list! It is the hardest available wood in Canada, and one of the hardest on the entire planet. It is the hardest one used for flooring and decking. Rest assured that your wood will not scratch or dent and will last a lifetime!