HARDNESS PHYSICAL PROPERTIES OF WOOD Hardness is a most important property of wood, since resistance to wear is necessary for a large number of purposes. In the Forest Service tests, hardness is determined by the weight required to force a steel ball .444 of an inch in diameter one-half its diameter into the wood. The tests upon green wood give the results shown in Table 8, the species being arranged from the softest to the hardest as expressed by the pressure in pounds necessary to make the required indentation.
The hardwoods as a class average from two to three times as hard as the softwoods. The hardest softwood, longleaf pine, is harder than basswood., buckeye, willow, butternut, and red cherry; but it is only about one-fourth as hard as osage orange, the hardest hardwood in the list. Their softness and ease of working make the softwoods as valuable for many purposes as are the hardwoods for other purposes.