This blog post is to accompany my recent video on You-Tube in which I sawed up a small apple log. Below is a pic of the wood hardness scale which is also known as the Janka Scale
The scale was developed as a means for displaying the results of the Janka hardness test. The test uses a 2″ x 2″ x 6″ piece of wood and a 0.444″ steel ball to determine how hard the wood is. The test figures out how many pounds per square inch, or PSI, of force is needed to push the steel ball half way into the wood plank.
As you can see above Apple for some reason is not on their scale but after some research I found it on another wood database site. According to their site Apple has a Janka rating of 1,730. This puts apple just below of Hickory but above other common hardwoods I saw at my mill.
Hope this helps and gives you all a better understanding on how wood density is measured.