ENTS: The Janka hardness test for wood is an interesting measure--it is the amount of force required to embed a 0.444 inch diameter steel ball in wood to half its diameter. It was developed to rate woods for resistance to denting when used for flooring. See its description and a list of wood hardness at this website: http://en.wikipedia.org/wiki/Janka_hardness_test
Lignum vitae comes out at the top of the list at 4500 pounds-force, compared to 1700 for black locust and 1450 for sugar maple. There are many tropical woods in the 2000-3700 pounds-force range. Regarding density, actually no wood approaches iron, which has a specific gravity of 7.87, so that a cubic foot of it weighs 491 pounds at room temperature, compared to 81.1 pounds for Lignum vitae. Balsa wood has a specific gravity of 0.2, so a cubic foot of it weighs 12.5 pounds, although keep in mind that all these statistics are the average of several tests, and that there is variability within each species. The matter in a typical neutron star is much denser than any known wood, with a specific gravity of 370-590 trillion, so that a cubic foot would weigh 190-300 trillion tons. Lee Timothy Zelazo wrote: > Guaiacum officinale, Lignum vitae is the hardest, heaviest and > closest-grained wood known and has a density almost equal to iron. > The weight is about 83 lbs. per cubic foot with a specific gravity of > 1.3. It also has the ability to withstand the great working pressue > of 2,000 lbs. per square inch and has resistance to the action of many > mild chemicals and acids. One application is for propeller-shaft > bearings in the largest liners. > > There are about eight distinct botanical species which are listed and > referred to as ironwoods. A few are Billian, Hophornbeam Eastern, > Ipil, Mesua, Pau d'Arco, Pau Ferro, Pyinkado, Quebracho, and Hornbeam > European. The common name "ironwood" is generally applied to whatever > wood in any particular section of the country is considered the > densest and the hardest. > > On Sat, Oct 31, 2009 at 2:56 PM, Timothy Zelazo <[email protected] > <mailto:[email protected]>> wrote: > > Cornus florida has a cubic weight per foot of 50 lbs. also used > for golf-club heads. > > Xylia xylocarpa, Pyinkado known as the iron wood of Burma weighs > 70 to 81 lbs. per cubic foot. > > Andira inermis, Partridge wood is about 75 lbs. per cubic foot > which emanates from Venezuela and Colombia. > > Prosopis glandulosa, Mesquite averages 55 lbs. per cu. ft. and > found in Arizona, Texas, and Oklahoma. > > Carpinus betulus, European Hornbeam is considered one of the > hardest woods growing in England. > > Ostyra virginiana, Eastern Hophornbeam is about 51 lbs per cu ft. > > Russ, thanks for the walking stick info. I've experienced the > same results when working the species you mentioned. > > Tim > > > > On Sat, Oct 31, 2009 at 2:21 PM, <[email protected] > <mailto:[email protected]>> wrote: > > ENTS: > > Of all the smaller eastern trees I would give dogwood, Cornus > florida a vote for one of the hardest woods. Over the years I > have used all sorts of woods for walking sticks and I have > found that dogwood does not split or splinter like hickory and > it doesn't shred or warp like hophornbeam. Hornbeam, Carpinus > caroliniana, seems to be fairly soft, it is easy to cut with a > knife it splits extremely easily and it will rot while you are > looking at it. > > Ostrya viginiana, hophornbeam splits extremely easily and > warps very badly. > > Walking sticks made out of dogwood never split on the point > end and with daily use will wear at a rate of less than half > an inch a year. Nothing else compares in terms of wear and no > tree I have tried for a walking stick has been more stable > than dogwood is once it has seasoned. > > Oak and ash walking sticks break much easier than dogwood and > are much heavier > > If you make a walking stick out of dogwood it is best to dig > out the entire tree and trim the roots with loppers. The best > size tree is, usually about 1" in diameter and has a straight > stem for at least four feet above the root collar. Carve the > handle out of the root ball. You can almost always get a very > comfortable hook to it. In my walks around the steep hills of > WV a dogwood walking stick has become my third leg....the one > that never slips. > > When freshly, cut a dogwood tree can be carved into a walking > stick with just a jack knife but once it dries it is like > trying to carve bone. > > When completely dried the wood is very light, which would mean > it is weak if one of the measures of strength is density. > > The walking stick in the photo is over five years old. The > patina that develops from long term use makes it very > comfortable to hold and after several years of use it becomes > a fairly reliable tool.....that hook on the end is extremely > helpful to pull the tip of a 10' high limb down close enough > to tie plastic ribbon when you are marking a trail in dense > brush. > > Other woods may be slightly harder in certain uses but nothing > I've encountered compares to the utility of a dogwood tree. > > > Russ > > > -----Original Message----- > From: Timothy Zelazo <[email protected] > <mailto:[email protected]>> > To: [email protected] <mailto:[email protected]> > Sent: Sat, Oct 31, 2009 1:52 pm > Subject: [ENTS] Re: What's the hardest hardwood? > > Carpinus caroliniana is American hornbeam (bluebeech, water > beech) and Ostrya virginiana is Eastern hophornbeam and had > the common name "ironwood" often applied to this species. The > Textbook of Dendrology by Harlow and Harrar Fifth Edition > published by McGraw-Hill. This was the info they were pushing > over thirty years ago when I studied forestry. The two trees > look very different in the forest. > > On Sat, Oct 31, 2009 at 1:36 PM, Josh Kelly > <[email protected] > <mailto:[email protected]>> wrote: > > > Don, > > On the contrary, I think I noted hop hornbeam (Ostrya > virgiana) in my > earlier post. > > Josh > > On Oct 31, 1:11 pm, DON BERTOLETTE <[email protected] > <mailto:[email protected]>> wrote: > > Josh- > > > > I guess that 'ironwood' (aka eastern hophornmeam, > American hornbeam, Ostrya virginiana; member of the > Betulaceae), member of the doesn't rate in this exotic group? > > > > -Don > > > . 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