Wood- how hard is hard?

April 30, 2017

An ash baseball bat to illustrate the hardness of wood types

I am routinely asked how hard a certain wood is - whether it's walnut, maple, purpleheart, etc. I usually answer with, " Well, hard maple is harder than walnut, but not as hard as purpleheart " or words to that effect. It would be nice to designate hardness with a value other than "more than and less than" relationship. Well, there is. Some smart fella long before my time came up with the Janka hardness test that provides the associated numbers.

 So, you ask, what high faluting test do they use to determine the hardness of wood for these results? Well . . . 

The test measures the force required to embed an 11.28 mm (.444 in) steel ball into wood to half the ball's diameter. Pretty simple but it assigns some values to the wood hardness that can be appreciated. 

For example, most people know that oak is very hard. Red Oak has a score of 1290. Hard maple is hard - hence the name. But to look at it's score of 1450 is to realize that it is harder than oak. I make some of our products out of Purpleheart and it is very hard and weighs more than other woods. Purpleheart's score of 1860 means that it is 1.44 times harder than oak. Now that is hard!

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