The Janka hardness test measures the resistance of a sample of wood to denting and wear. It measures the force required to embed a small steel ball steel ball into wood to half the ball's diameter. This method leaves an indentation in the wood and determines whether a species is suitable for use as flooring. The hardness of wood varies with the direction of the grain of the wood.There are various presentations of the Janka hardness number. The chart below reveals that Brazilian Cherry is the hardest wood. Douglas Fir is the softest. BH offers Brazilian Cherry but not Douglas Fir.