To compare the hardness of different types of wood, identify their Janka hardness rating or, if the rating is unavailable or unlisted, test the types of wood with the Janka hardness test. These ratings can be found on the Janka Hardness Scale, which lists a variety of wood species with their respective numerical hardness rating determined by the Janka hardness test.
To conduct the Janka hardness test, take a portion of the species of wood in question and press an 11.28 millimeter metal ball into the wood's surface. Measure the force being used on the ball. Increase the force on the ball until it has become embedded up to half the ball's diameter. The measure of the force that is used to make this indentation.
The Janka hardness test can be performed on two different parts of a given piece of wood. To get the side hardness of a type of wood, perform the Janka hardness test perpendicular to the grain of the wood. To get the end hardness of a type of wood, perform the test on the cut surface of a stump.
When comparing an accessible Janka rating to one taken on site, confirm that both ratings are taken using the same unit of measurement. The two most common units of measurement for the Janka hardness test are pounds-force and kilograms-force.