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
Hard Maple
1450
Natural Bamboo
1380
Australian Cypress
1375
White Oak
1360
Ash
1320
Beech
1300
Red Oak
1290
Caribbean Heart Pine
1280
Heart Pine
1225
Carbonized Bamboo
1180
Eucalyptus
1125
American (Black) Walnut
1010
American Cherry
950
Southern Yellow Pine
870
 

Question:

What exerts more pressure-per-square inch when walking on a floor:
a 100 lb woman in high heels
-or-
 a 6,000 lb elephant in bare feet?

Answer:

The woman!

Stiletto heels have a surface area of about 1/16 of a square inch. Elephants, unlike humans, walk with two feet on the ground at a time. Each foot is about 40 square inches. Thus, the woman "wins" by far with more than 1,500 psi versus 75 psi for the elephant.

Translation:

High heels will indent nearly every wood specie to some degree and should not be worn on wood flooring or stair treads.