Janka Hardness Scale
Wood Species Selection : Hardness
The Janka hardness test measures the hardness of wood.
It involves measuring the force required to embed a 11.28 millimeter (0.444 inch) steel ball into wood to half its diameter. This method was chosen so that the result would leave an indention 100 square millimeters in size. It is one of the best measures of the ability of a wood species to withstand denting and wear. It is also a good indicator of how hard a species is to saw or nail.
The hardness of wood usually varies with the direction of the wood grain. If testing is done on the surface of a plank, perpendicular to the grain, the test is said to be of "side hardness." Testing the cut surface of a stump would be called a test of "end hardness."
The results are stated in various ways, which can lead to confusion, especially when the name of the actual units employed is often not attached. In the United States, the measurement is in pounds-force (lbf). Sometimes the results are treated as units, e.g., "660 Janka". A common use of Janka hardness ratings is to determine whether a species is suitable for use as flooring.
|Janka Hardness (Pounds-Force)|
|Ipe / Brazilian Walnut||3684|
|Cumaru / Brazilian Teak||3540|
|Brazilian Cherry / Jatoba||2350|
|Santos Mahogany / Cabreuva||2200|
|Tigerwood / Goncalo Alves||1850|
|Hickory / Pecan / Satinwood||1820|
|Sapele / Sapelli||1510|
|Caribbean Heart Pine||1280|
|American (Black) Walnut||1010|
|Southern Yellow Pine||870|