Heat Treating Wood

S

sharp69

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Jul 18, 2013
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I'd like to heat treat wood. I know that when all wood spears were state of the art, they'd char the end of a slim pole, then sharpen it. Don't want to actually blacken the wood, because one use would be slabs for a specialized knife. Another would be the business end of a wooden mallet. I'm thinking that because of it's density and cost, oak would be ideal, if it responds well to heat toughening. Otherwise, I'm open to other woods, such as rock maple. I'm thinking oil finish, since both are rough use tools. Who's done it, and would be willing to explain how, or refer me to a thread. PMs are fine, also.
 
I think fire hardening only works for green wood.

You take a nice straight, flexible (tough but soft) limb, and basically dry the sharpened point.

I have been a woodworker for a few decades, and that's the only reference I've ever heard of.

Trying to "heat treat" dry wood simply burns the wood or over-dries it, which means it probably turns checks into cracks.
 
Are you buying wood for this because It will already be dry. Theres no such thing as fire hardening, It's just a cool sounding name you saw on a survival show for drying out wood. If you have a kiln meant for drying out wood thats the the fast option. The other option is letting it sit for a year or two.

Edit: I reread your post and it looks like you are in fact buying it. Its already dry, all you will do is ruin it by trying to dry it more.
 
Fire hardening ,if that's the proper term , was done in ancient times .Before they had spear tips of stone they fire hardened them .Does it work ? Yes Can it be done on dried wood ? Yes
I made a miniature 'hawk and a friend was looking at it .He said how did you get the handle so hard ? This was a piece of hard maple . I laughed and told him " I fire hardened it " All I had was a propane torch and I carefully played that back and forth along the wood .Be patient. You'll get some charing so that can be sanded off.
The process might be found on one of the primative websites ,do some searching.
 
We get fire salvage wood here every once in a while.
The only woods that I have seen that were noticably harder were sappy woods where the heat from a forest fire set the pitch in the wood. The burnt maple I have worked with (Western Big Leaf Maple) was no harder than the normal stuff. Bugs (powderpost beetles) still like the burnt Maple.
There used to be a guy on ebay selling baked maple but I have never seen it in person.
My thoughts are that Eastern Rock Maple with an oil finish will be plenty hard without "heat treating".
 
I've bought some of an eBay vendor's kiln baked maple. I can't really speak for the hardness as I haven't used enough maple to be able to tell, but he does claim that it:

"This wood has been "Cooked" or "Baked" using a special heat treatment process. This process is applied to already kiln dried wood and alters the wood at the cellular level. The wood is heated to temperatures of 185 degrees Celsius or 365F. This collapse the cells inside the wood making the wood more stable and resistant to moister fluctuations. It also increases the density of the wood. The resulting wood is dried to about 4-6% relative humidity! And most important of all is the color transformation and figure enhancement which you can see in the pictures. This is red maple with an exotic wood color. I call it Hades Roasted Maple in a "medium roast". "

I've used it a couple if times and the dark color stays throughout the piece- this knife is simply finished with tung oil:
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Thank you all for the responses. Cuts Like, that maple is just what I was thinking about. Like a Kaintuckee long rifle, without having to use direct flame. As for "survival shows," not my thing. After half a lifetime as a woodsman, I'm already schooled in that.
 
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CUTS LIKE A KRIS said:
I've bought some of an eBay vendor's kiln baked maple. I can't really speak for the hardness as I haven't used enough maple to be able to tell, but he does claim that it:

"This wood has been "Cooked" or "Baked" using a special heat treatment process. This process is applied to already kiln dried wood and alters the wood at the cellular level. The wood is heated to temperatures of 185 degrees Celsius or 365F. This collapse the cells inside the wood making the wood more stable and resistant to moister fluctuations. It also increases the density of the wood. The resulting wood is dried to about 4-6% relative humidity! And most important of all is the color transformation and figure enhancement which you can see in the pictures. This is red maple with an exotic wood color. I call it Hades Roasted Maple in a "medium roast". "
Click to expand...
I believe the process is called torrefaction, that is, the wood has been torrefied... http://www.silvatimber.co.uk/media/pdfs/torrefied-wood/torrefied-wood-explained.pdf
Also http://www.mectorrefaction.com/advantages.html
 
We hardened green wood as kids- we could throw spears with fire hardened
points and make them stick in another hardwood. It definitely works, we would
heat them to char in a fire, carve off the char and they were good to go.
Ken.
 
I think this is wishful thinking.

If you want harder wood, use a harder species. And/or you can always stain it a desired color or have it stabilized, which would probably be priced comparably. It's scientifically proven to work. That's why it's so popular.

Wood at 4-6% humidity will move as much as wood with 15- 18% moisture, it will just be in the opposite direction.

Of course, if you're one of the extremely few who try to market this, you'll have to say something positive about it.

If it worked it would have been mainstream for hundreds of years by now.

JMHO.
 
Burl Source said:
We get fire salvage wood here every once in a while.
The only woods that I have seen that were noticably harder were sappy woods where the heat from a forest fire set the pitch in the wood. The burnt maple I have worked with (Western Big Leaf Maple) was no harder than the normal stuff. Bugs (powderpost beetles) still like the burnt Maple.
There used to be a guy on ebay selling baked maple but I have never seen it in person.
My thoughts are that Eastern Rock Maple with an oil finish will be plenty hard without "heat treating".
Click to expand...

Yes Eastern rock maple is actually used in industrial applications for its "hardness" , its great, great stuff
 
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