CALCULATING THE HARDNESS OF WOOD FLOORS
Asking yourself the right questions is key to buying the wood flooring that best meets your needs. Some of the most important questions include: How will this wood floor be used? Is it for commercial use? Do you have young children or animals? The answers will guide you to the best species for your wood floor. Obviously, the harder the wood, the tougher it will be and the more resistant it will be to impact. A hardness scale, called the Janka Hardness Test, classifies all wood species used in flooring. Here is an example.
JANKA HARDNESS TEST
*The Janka Hardness Test determines the resistance of a wood species to indentation and wear. It measures the force required to embed a 0.444 in. (11.284 mm) steel ball halfway into the wood. The number indicates the pressure (in pounds) needed to embed the ball. The harder the wood, the more pounds are needed. This method, which leaves an indent in the wood being tested, was developed by an Austrian dendrologist, Gabriel Janka (1864–1932), at the very beginning of the 20th century.
Source : Wikipedia