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The Janka Hardness Test

The hardness of a timber is measured by the Janka hardness test. This test measures the force required to embed an 11.28mm (0.444 in) steel ball to half its depth into wood. The Janka hardness test is the industry standard for determining the ability of a particular timber species to withstand denting and wear.
In Australia, Janka results are displayed in either newtons (N) or kilonewtons (kN).

Species Janka Rating (kN)
American Oak 6.0
Australian Beech 7.5
Bamboo (horizontal) 5.87
Bamboo (vertical) 6.58
Bamboo (strand woven) 16.10
Blackbutt 9.1
Brazilian Walnut 16.37
Brushbox 9.5
Cypress Pine 6.1
Flooded / Rose Gum 7.5
Forest Reds 9.1
Ironbark 14.0
Grey Box 15.0
Jarrah 8.5
Karri 9.0
Merbau 8.56
Messmate 7.1
New England Oak 6.1
Northern Beech 7.5
Red Mahogany 12.0
Ribbon Gum 6.1
Spotted Gum 11.0
Stringybark 8.1
Sydney Blue Gum 9.01
Tallowwood 8.6
Tasmanian Oak 5.5
Turpentine 12.0
Victorian Ash 4.49

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