The Forestry Forum

From time to time the subject of the hardness of some of our hardwoods comes up.  There is a test called the Janka Hardness Test where a steel ball is pressed into the wood and the amount of force required is measured.  The result is called the Janka hardness of that wood.  Here is a list of common North American hardwoods and their Janka Hardness.  You may be surprised by some of the values.

The higher the number, the harder the wood.  I have seen some stated results that shows osage orange is the hardest and some that show that live oak is the hardest.  In any case, they are both about equally hard.  One surprise to me was the range of hardness on the elms and in the Southern bottomland species cherrybark oak which is the best quality red oak in the deep South.  Hophornbeam and American hornbeam are both commonly called "ironwood", but they are not the hardest hardwods.  Just goes to show that common names are many times not accurate since iron is harder than wood :). 

Osage Orange	2760
Live oak	2680
Mesquite	2345
Persimmon	2300
Dogwood	2150
Pignut hickory	2140
Mockernut hickory	1970
Hophornbeam	1860
American hornbeam	1860
Serviceberry	1800
Black locust	1700
Elm winged	1540
Red Oak cherrybark	1480
Maple sugar	1450
Oak white	1360
Elm rock	1320
Red Oak northern	1290
Walnut black	1010
Maple red	950
Cherry	950
Elm american	830

I've moved stuff around in the shop but I like to keep stuff like this and metal melting temps on a piece of paper on the wall somewhere. I've also got a picture with the names of different parts of a log, to remind me what the heck you guys are talking about. I think since I've moved stuff I've managed to misplace all of those so this is cool! Thanks for sharing!

Serviceberry? Which one!  :D

I have a couple small chunks kicking around and while I have never used them for anything...at all, they are very heavy for their size and given the relationship between density and hardness I'm surprised to see it rated so low.

Clark