The Janka hardness chart was created as a result of the Janka hardness test. The Janka test measures the hardness of wood so
that wood species can be compared to one another. The Janka chart is commonly used in the flooring industry to compare
hardwood flooring types. Although not exact, the scale is a good reference for which hardwood can better withstand denting
and wear when compared with another wood species. The higher the Janka rating, the more dent and wear resistant a particular
wood is. In addition, the rating can determine a wood’s ability to be sawn or nailed. The higher the rating usually
means it is harder to work with then the woods lower in the Janka hardness scale.
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The Janka process of measuring the hardness of wood begins with embedding a steel ball (0.444 inches in size) until it
reaches halfway of its diameter into the wood. The measurement in America is done in pounds-force (lbf) and the results are
put into the Janka scale or chart such as the one below. The American chart has been accepted by the global flooring
community as a common reference for the hardness of wood. As an example, red oak hardwood has a Janka rating of 1260, meaning
it took 1260 pounds of force to embed the steel ball half way into the sample piece of red oak. Hardwood flooring species are
usually compared to red oak as the basis, such as; Brazilian Cherry (Jatoba) hardwood flooring is 224
times harder than a red oak floor.
The hardness of the wood can depend on the direction of the wood grain that is supplied for the test. Flat grain or
horizontal grain is the normal wood grain used to compare woods of different species. The vertical grain of wood is also
tested, but is not normally displayed in the Janka hardness chart. The most common Janka test and the one displayed in most
hardness charts, is the test that has the ball embedded in the face of the wood, and not on the edges or the ends.
