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Flame Tempering of wood

Started by Spruce_Goose, August 08, 2013, 08:58:15 PM

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Spruce_Goose

Hi all.
Is anyone here familiar with the term or process of 'flame tempering' wood. This would be used in such applications as archery bows, tool handles, bats, etc. It is supposed to make it stronger, but I'm not sure exactly why or how it is best done (torch, open flame, coals, etc.)

I am familiar with the concept of kiln drying strengthening wood through the extreme dryness it causes (dry wood = stronger wood). And I am also familiar with the concept of wood becoming more supple through high heat (often applied through steam). I am guessing flame tempering is working off one or both of those concepts. (supple wood being beneficial for certain items because it will bend further before breaking). I also have read that flame tempering may affect the cell structure, causing it to be tighter...

beenthere

A flame would darken the color of the wood, and may give the "perception" that the wood is stronger.

Often, "perception" sells and is a good marketing gimick.

Just my opinion on it.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

longtime lurker

The process is called fire hardening.
There is no "perception" about it, it's a process that humans have used for thousands of years... as in since the stone age... to case harden things like spear and arrow points. Basicly it achieves hardening by two means... one is that the wood dries which obviously makes it stronger. The other is that the mix of oleoresins released from the wood mixed with charcoal that forms on the surface can be polished to a sharper edge then straight timber alone.
The quickest way to make a million dollars with a sawmill is to start with two million.

Ianab

Like Longtime says....

From Wikipedia

QuoteFire hardening, also known as "fire-polishing", is the process of removing moisture from wood, changing its structure and material properties, by slowly and lightly charring it over a fire. This makes a point, like that of a spear, or an edge, like that of a knife, more durable.
Pre-historic weaponmakers would rub the end of a selected wood pole against a smooth rock surface until a point was achieved. Then the point was heated in a fire, making sure to thrust the point into the coals. This put a light coating of carbon on the surface, which was then polished with a special stone, which ground fine particles of stone into the pitch which had been brought to the surface of the wood by the fire. Subsequent firings and polishings of the wooden tip of the spear would eventually form a hardened glaze consisting of pitch, wood particles and carbon on the tip which could eventually be even harder than a copper tip. This kind of primitive technology was available to primitive humans for at least 400,000 years, long before flint or stone points were used.

It was done by native cultures like the Australian Aborigines, Polynesians etc that might not have had access to flint or metals to make spears. I bet Bear Gryls has done an episode on it at some point, and eaten whatever he was able to spear  :D

Ian
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

5quarter

there was a type of Shillelagh made by the Irish peasantry that was made from the root and trunk of a blackthorn tree. they would sharpen the ends of the root projections and then harden them in fire. It was rumoured that a well made Shillelagh could pierce plate armour. seems unlikely, but I wouldn't want to test it... ;)
What is this leisure time of which you speak?
Blue Harbor Refinishing

GeneWengert-WoodDoc

When the western US was being surveyed--early to mid 1850s--, to mark the survey corners, they used an eastern hardwood species (a species that was not found in the West) stake that was buried and that had been well toasted in a fire.  This toasting insured that the wood would not decay.  I can recall even in 1960 that some of these stakes were found and, due to their legal importance, we were asked to I.D. them for species.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

LeeB

'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

Jemclimber

Yes Doc, we want to know the species? Please?
lt15

hackberry jake

https://www.facebook.com/TripleTreeWoodworks

EZ Boardwalk Jr. With 20hp Honda, 25' of track, and homemade setworks. 32x18 sawshed. 24x40 insulated shop. 30hp kubota with fel. 1978 Massey ferguson 230.

redprospector

Fire hardening is no joke!
I've got a job that I have to get back on that was burnt in the Scott Able fire in 2000. The land owner wants all the burnt snags, and blow downs mulched. I looked the job over pretty good, but being human I guess I was a little lazy and only sounded the down trees toward the bottom of the canyon. After 13 years they seemed to all be pretty rotten. Well, surprise, surprise. As I worked my way up the hill the logs, and snags got more & more solid, at least the SW White Pine. Some of this stuff is close to being petrified. I've changed my strategy on this project, and am going to skid the hard stuff and haul it to my place (for firewood I guess). I'll mulch everything that is soft enough.

Andy
1996 Timber King B-20 with 14' extension, Morgan Mini Scragg Mill, Fastline Band Scragg Mill (project), 1973 JD 440-b skidder, 2008 Bobcat T-320 with buckets, grapple, auger, Tushogg mulching head, etc., 2006 Fecon FTX-90L with Bull Hog 74SS head, 1994 Vermeer 1250 BC Chipper. A bunch of chainsaws.

GeneWengert-WoodDoc

The surveyor could select the species.  Some of them included cherry, hickory, walnut and locust...it depended on what species were native to the area they were surveying. 

At times they also used living trees as reference points, giving the species, but after 100 more years, these trees often were gone, but an old stump might have still been there and so we did some ID work on these stumps too.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

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