Janka hardness test Janka hardness test The Janka hardness test (from the Austrian-born emigrant Gabriel Janka, 1864-1932) measures the resistance of a sample of wood to denting and wear. It measures the force required to embed an diameter steel ball halfway into a sample of wood. A common use of Janka hardness ratings is to determine whether a species is suitable for use as flooring. The hardness of wood varies with the direction of the wood grain. Testing on the surface of a plank, perpendicular to the grain, is said to be of "side hardness". Testing the cut surface of a stump is
Walter Janka Walter Janka Walter Janka (born in Chemnitz 29 April 1914, died in Kleinmachnow 17 March 1994) was a German communist, political activist and writer who became a publisher. Janka is notable for having spent time incarcerated as a political prisoner under the rule of the Nazis and later imprisoned under suspicion of counter-revolutionary activities by the Supreme Court of East Germany, in both cases serving most of his sentence at Bautzen prison. Walter Janka was one of six children born to a Tool and die maker called Adalbert Janka. He attended junior school from 1920 till 1928. Between 1928 and