Fire hardened hickory

[Flem]

Thanks Eric. I should have elaborated, rather than made vague inquiries. Context is everything and I was giving Mike grief about lack of reference in his post and then did the same thing myself. Needless to say I don't need any help to look like a fool
I did go to check out the DVD and watched the trailer. Funny thing, if I did not know the subject matter of the video, I would have been clueless they are fire hardening wood. Looks to be a lot of info out there on that subject. Is there an advantage to using an open flame, over other heat sources?
Sounds like the primary objective is to remove all moisture, which will tighten the grain structure and increase intercellular bonding. It would have to loose some elasticity from cooking the connective tissue, but gain compressive strength?

[Onehair]

Flem , I tried somewhat of an open flame at first and you just scorch the surface. According to the guys that made the video it is a low slow heat taking about 2 hours. That I found to be true. The treatment on my hickory when almost 2/3 through. They even have made some sweetgum bows shooting over 170 fps with 10gr per lb of draw
(47#). As I have plenty Sweetgum I have treated a piece. If it doesn't explode and crack my skull I'll post the results. I saw a few trying with Osage but the video says it actually is bad for Osage. Have a great 4th

[darin putman]

    Flem removing all moisture from the wood seems to be exactly what it does after heating hickory from 2- 2 1/2 hours it will show zero moisture with my pinless wagner meter.   
    Onehair I am looking forward to trying sweetgum myself, I have plenty just need to cut. I have ruined a couple osage staves so far, but cause was treating it like hickory. With hickory you can literally scrap the charred wood off the belly and continue to make a bow. Well most of the time I have trashed a couple  of them by pushing it too far.

[Mad Max]

Marc St Louis style
I did ash with a heat gun about 7" away from the belly on a bracket to hold the heat gun, It took about 2 hours for each limb and you can see whats going on with the wood.
I did some minor scraping and sanding and finished tiller from the sides.
2-1/2" at the widest point.

[darin putman]

Mad Max, looks like you did a very good job with that heat gun. I guess the main advantage I can see   other than time and patience for myself heating over a bed of coils is that the entire bow has heat applied for however long one chooses to heat the bow.
   Not taking anything away from anyone that uses a heat gun. That was the only way I  knew to do it up untill a few months ago. I was never able to turn out a bow treated as evenly and dark as the one you showed though, be it due to either a lack of patience or skill. Probably a little of both on my part.

[Mad Max]

I was in the bow room work on other stuff while it was being heat treated.
I don't think I could stand there and wait for it, so it worked out for me.

[Flem]

Have any of you guys checked the moisture content 6 months or a year later?
Curious if it eventually comes back to equilibrium.

[darin putman]

Flem, I have checked my bows they are not but about 2-4 months out. The humidity in my shop has averaged as high as 85 percent and my bows have headed back towards equilibrium. The bellies will be  lower than the back, meaning belly @5-7 perc.  and the back@7-9 per. These are hickory and from what I can tell the wood that is fire hardened is staying lower than the wood that is not[back]. In the video I noticed his bows looked wider than mine and would probably be thinner than mine. I have thought of making a wider thinner bow and seeing how it turned out but can't seem to talk myself into it. My bows are a little less than 1/2"  thick at the fades to about 1/4" thick at the tips. Am happy with the process and look forward to trying some sweetgum as soon as I get around to cutting and drying.

[Mad Max]

Have any of you guys checked the moisture content 6 months or a year later?
Curious if it eventually comes back to equilibrium.

The how to is in the Bowyer's Bible Volume 4
Marc St, Louis filled the heat treated grain with "spruce gum and turpentine" while it was Hot.
I used thinned down Shellac as I was going along.

[Flem]

Giving this thread a revisit. I was digging thru my boneyard and found a Maple stick I started working on about 15yrs ago. Its a little soiled from being jammed in a corner with other chunks of wood, pipe and scrap metal. Figured it deserved a little respect, so I am going to finish it up.

I was thinking it might be a good candidate for the fire treatment and was hoping to get some advice.
Do you guys cook the belly side only?
How close to tillered should it be before cooking?
Do you coat or seal the wood before cooking?
Any body tried cooking in a temp controlled furnace or oven arrangement?  Which would of course cook the whole thing, but I'm thinking the whole thing is subject to elevated temps anyways. A couple hours over a bed of coals is going to cook a 1/2"-1" thick slat of wood, medium well.

[darin putman]

 Flem I try to get my bows as close to finish as I can without stressing the wood (think extremely floor tillered). I was lucky to have a few hickory staves from the same tree I cut several years ago, so I just pushed it progressively closer and closer to finish size as I had a good idea how the wood would react.
   I personally heat my blanks bent on a caul, belly side towards the coals. It is just like any other heat treat as far as I can tell in that if you start off with a thick bow blank , heat it and scrap off a lot of your treated wood you will loose some of the effects of the heat treatment. That has not been a problem on the inner portions of the limb but was out towards the tips for me. The reason for this was because my heat was farther away from my tips and was not heated through. I built my bed for my coals up to be more in line with my caul towards the tips and it helped this a lot.
   I have also tillered one down scraping too much wood off and put it back on caul and repeated the process.
   I have had good luck with hickory but have also burnt up a few hickory, osage staves and cauls by pushing it too much.
   Good luck, kinda slowed down in my shop right now as summer brings with it lots of other responsibilities around here. Plus my shop is an oven most days.

[hunting badger]

I bought the video and want to try this method. Darin I'm glad you tried it and got positive results, It's always good to get reaffirmation from a neutral party. Here in Alaska we don't have much for native woods to work with, but I'm going to try this method on our native white birch and see if I can get positive results. Thanks for posting!!

[darin putman]

  Thanks Hunting badger, look forward to seeing your results. I plan on trying a couple more species.
   The main thing that got me interested was the hydroscopic effect on Hickory. It does slow it down as I've noticed the back of my bows gaining moisture at a faster rate than the bellies. I have even thought about cooking the back of a bow slowly and deliberatly just to see if it can be done enough to make a difference. I know thats not something most would try, but I'm not talking scorching the back, just enough heat for a slight color change. I know I've made bows that I accidently got the back scorching hot and wondered if they would survive and they did. I also know the back can take a lot of heat as long as it isn't scorched. I don't know if it can be done enough to slow water absorption on hickory but I have a strange suspicion that it can.
  Anyone on here ever heated the back of a bow enough for a slight color change on purpose? If so would love to hear results.