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 exile in Mexico, where together with Paul Merker and Alexander Abusch he founded the "Free Germany" (""Freies Deutschland"") movement. In Mexico he ran the publishing business "El Libro Libre", which also employed the exiled German writer Anna Seghers. In 1946 Janka took on the leadership of the Mexican section of the German Communist party (KPD). After the end of the Second World War Janka returned, in April 1947, to what was Soviet occupation zone, later to become German Democratic Repbulic in 1949. In 1947 he married his long-standing partner, a translator called Charlotte (Lotte) Scholz. The couples' two children, André