Janka Hardness
Also known as: wood hardness, resistance to indentation
The Janka hardness test measures wood resistance to indentation and denting by forcing a steel ball into the wood surface under standard load. Developed by Gabriel Janka in 1934, the test is a simple, nondestructive indicator of wood durability, wear resistance, and suitability for flooring, furniture, and other wear-prone applications. Janka hardness is one of the most widely used wood property metrics in wood science and commerce.
Key highlights
- Simple, fast, and widely standardized (ASTM D1037); enables direct species comparison
- Results are widely published for hundreds of species, facilitating selection
- Non-destructive to the overall piece; only a small indentation is created
Intuition
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How it works
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When to use it
Use the Janka hardness test when selecting wood species for applications requiring resistance to surface indentation and wear, such as flooring, furniture, or tool handles, or when comparing mechanical properties across species and growing conditions.
Strengths & limitations
- Simple, fast, and widely standardized (ASTM D1037); enables direct species comparison
- Results are widely published for hundreds of species, facilitating selection
- Non-destructive to the overall piece; only a small indentation is created
- Measures only surface resistance to indentation; does not capture tensile or compressive strength
- Values depend on grain orientation (radial vs. tangential vs. end grain) and moisture content
- Not suitable for very thin samples or veneers
Sources
- 1.ASTM D1037-21. (2021). Standard test methods for evaluating properties of wood-base fiber and particle panel materials. ASTM International.
- 2.American Hardwood Export Council. (2012). Wood hardness ratings. Technical Report.
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Cite this page
ScholarGate. (2026, June 3). Janka Hardness. ScholarGate. https://scholargate.app/forestry/janka-hardness