Wood lexiconFoto © by depositphotos.com | Kotenko

Janka-Hardness

Search for glossary terms (regular expression allowed)
Term Definition
Janka-Hardness

What is the Janka Hardness?

The Janka hardness is a method for determining the hardness of wood, indicating how resistant the material is to indentations. It measures the amount of force required to press a steel ball with a diameter of 11.28 mm halfway into the wood. The required force, measured in kilonewtons (kN), provides information on the wood's resistance to pressure marks. The higher the Janka value, the harder and more resistant the wood.

 

 Janka hardness testIllustration janka hardness test | Photo © by Hugo Kämpf

The Janka Hardness Test

In the Janka hardness test, the steel ball is evenly pressed into the wood until half the ball diameter is embedded. The test provides comparable values that reflect the hardness of various wood types. For example, oak, with a Janka value of about 6 to 7 kN, is significantly harder than softwoods like pine. Extremely hard tropical woods, such as ipe or bongossi, can reach values over 12 kN.

This test is especially relevant for wood used in high-wear areas, such as flooring or furniture. The higher the Janka hardness value, the less prone the wood is to scratches and dents in everyday use.

 

Janka Hardness vs. Brinell Hardness

In addition to the Janka hardness, there is also the Brinell hardness, a similar method often used for metals but also applicable to wood. Unlike the Janka hardness, where the ball is pressed only halfway, the Brinell test measures the indentation depth of the entire ball and calculates the hardness value based on the size of the resulting impression. Both tests provide helpful information about material resistance, with the Janka test specifically developed for wood and the Brinell test more broadly applied to metals and other materials.

 

Verschiedene Holzarten nach der Janka-Härte sortiert 

Wood species Janka-hardness in lbf (USA) Janka-hardness in kilonewtons (kN)
Australian casuarina 5000 22.500
Pockwood 4500 20.000
Ebony tree 3220 14.323
Fibre bamboo 3000 14.002
Blue wood 2900 12.900
Merbau tree 1925 8.563
Swamp oak 1510 6.717
Sugar maple tree 1450 6.450
Bamboo 1380 6.139
Ornamental cypress 1375 6.116
American white oak 1360 6.050
White ash 1320 5.872
Red oak 1290 5.738
Yellow birch 1260 5.605
Teak tree 1155 5.138
Black walnut 1010 4.493
Paper birch 910 4.048
Cedar tree 900 4.003
African Mahogany 830 3.692
Frankincense pine 690 3.069
Douglas fir tree 660 2.936
Red alder tree 590 2.624
Chestnut 540 2.402
Black spruce 520 2.313
Coastal fir 490 2.180
Coast redwood 480 2.135
Lime tree 410 1.824
Balsa fibre 100 0.445

 

In Summary - Explained Simply

The Janka hardness measures how resistant wood is to pressure marks, while the Brinell hardness is a more general test for indentation resistance. Both methods help assess material hardness, especially for high-stress areas like flooring or furniture.

 

Related article:

Brinell hardness

Synonyms: Hardness test, wood strength test

We use cookies on our website. Some of them are essential for the operation of the site, while others help us to improve this site and the user experience (tracking cookies). You can decide for yourself whether you want to allow cookies or not. Please note that if you reject them, you may not be able to use all the functionalities of the site.