Janka Hardness Rating

janka hardness test embeds a steel ball into the wood
Image by Nasa-verve, Wikimedia Commons

The Janka hardness test is the international standard for measuring the resistance of a sample of wood to denting and wear. It's expressed in pounds-force (lbf). The test actually measures the force required to embed an 11.28mm (.444 in) diameter steel ball into wood to half the ball's diameter. It's commonly used to determine whether a species is suitable for use as flooring; however, we include it here and compare it to the rating of red oak to give you an idea of how hard a given wood is.

The hardness of a wood doesn't always translate in how difficult a wood is to work with. Generally speaking, the harder the wood the easier it is to finish and polish it.

The hardness of wood varies with the direction of the wood grain, and varies from piece to piece. So a Janka rating is an average of numerous tests performed on all directions and numerous pieces. Use the Janka hardness rating as guide, not a definitive answer.

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