Heat tape for protecting backs of bows

[Selfbowman]

When I heat a bow there will hardly ever be  char on  the wood any more. After probably a thousand hour on the heat gun you learn a few tricks no matter who you are. I use the barbecue test for steaks
For heat range. Heat the wood and put your fingers on the area heated. 1-2-3 whoa that’s 350 hands off. Keep the gun moving as Gary would say .   Then gently clamp if needed. Arvin

[willie]

You might need more than 300 degrees to heat-treat

  I was wondering about that, I guess it would take some experimenting. I am really curious if a longer lower temp heat treat might have more effects or not.

Steve,
longer times at lower temps could be a worthwhile experiment,  but I think a protective tape like you describe would only be effective if the heat treat times were very short.

perhaps your oven design could incorporate a floor that would allow the belly to be inside the oven, and the back to be outside the oven, or immersed in water or at least stay damp somehow

[scp]

I would not put the whole wooden bows or limbs in oven. I have been thinking about buying a "Mandolin Side Bending Silicone Heat Blanket w/Controller". I want to use it for dry bending limbs and tips. But it might be useful for heat treating as well. They are cheaper than the tape you are talking about.

[SLIMBOB]

There is a specific reason I bring this up. Made an Osage bow few years ago. 65 inch flat bow. I flipped the tips early, but towards the end I decided to go with a some pretty radical reflex.  Around 6 inches. It was a lever bow so some was in the non bending levers but some was along the working limb as well. I turned the dial up on the heat gun and did a pretty shallow, high temperature temper. The belly turned the color of dark chocolate.  It has held up well. Some pulled out over time but no more than any that were tempered deeper and more slowly. I have not measured it lately but it ended up with around 3 to 4 inches. This bow has made me ask this question.

[Badger]

There is a specific reason I bring this up. Made an Osage bow few years ago. 65 inch flat bow. I flipped the tips early, but towards the end I decided to go with a some pretty radical reflex.  Around 6 inches. It was a lever bow so some was in the non bending levers but some was along the working limb as well. I turned the dial up on the heat gun and did a pretty shallow, high temperature temper. The belly turned the color of dark chocolate.  It has held up well. Some pulled out over time but no more than any that were tempered deeper and more slowly. I have not measured it lately but it ended up with around 3 to 4 inches. This bow has made me ask this question.

  The bamboo link that Pat supplied does a pretty good job describing the changes that take place at different stages. I didn't read it in detail but plan to go back and reference it as needed.

[Marc St Louis]

There is a specific reason I bring this up. Made an Osage bow few years ago. 65 inch flat bow. I flipped the tips early, but towards the end I decided to go with a some pretty radical reflex.  Around 6 inches. It was a lever bow so some was in the non bending levers but some was along the working limb as well. I turned the dial up on the heat gun and did a pretty shallow, high temperature temper. The belly turned the color of dark chocolate.  It has held up well. Some pulled out over time but no more than any that were tempered deeper and more slowly. I have not measured it lately but it ended up with around 3 to 4 inches. This bow has made me ask this question.

I've not tempered a lot of Osage bows but from the ones I did I found that Osage reacts differently to heat than a white-wood.  It turns brown faster and the heat seems to penetrate faster, could be the quantity of oil in the wood does this.  I quick temper on HHB or Elm will not do much

[SLIMBOB]

I too see a difference in Osage and white woods when it comes to heat treating.  I will add Mulberry to that as I just finished one.  I did a fairly quick heat treat with a dark color, just as I would do Osage and most of the reflex has held up.  Maybe the oils do allow the heat to penetrate more quickly.  I haven't had the chance yet to read the post PatM posted but I will.

[dylanholderman]

I’d be worried about the tapes insulation ability too, the company I work for makes industrial kilns so we use similar products on a regular basis.

What you described sounds like it is meant to hold insulation in together, not provide insulation it self.

Something that might work in combination with said tape for you is some sort if ceramic fiber paper.
At work we have it down to 1/8” thick and anywhere from 1200-3000 F
It’s not cheap but a strip of that fiber would definitely be reusable a couple of times.
 

[Santanasaur]

I’ve always thought a salamander would be good for heat treating, basically a broiler oven open on both ends. I’m thinking just the radiation heating without all the convection should probably be better for not scorching the back. I like del’s idea of the blacksmiths clay or mud, that was my first thought as well. Maybe reusable putty could be made of silicone...

[willie]

Hi Steve

any further thoughts/experiments about this concept? I think a differential heat treat may be worth looking into

[Badger]

Hi Steve

any further thoughts/experiments about this concept? I think a differential heat treat may be worth looking into

   I wish I was as motivated as I was even 10 years ago. Sometimes I throw ideas out there and I don't always get around to trying them. I actually like the mud idea mentioned above, clay is easy to get and easy to wash off. A slower much longer bake is really what I would like to accomplish. Sometimes things happen when they hit a certain temp and sometimes things happen when they are held at a temp for a longer period of time. I recently bought a souz vide for cooking roasts mainly. I can cook a roast at about 134 degrees for 24 hours and it melts all the connective tissue that makes it tough. Something slow and low is what I am hoping to try with wood.

[Selfbowman]

Steve could this be done on a straight stave bow and then induce the reflex in another heat treatment ? Arvin

[Badger]

  Arvin, that is kind of what I was hoping for. Not really sure but I think so.

[willie]

a thought I had a while back when you first posted this thread was to bed your stave on the caul with the mud or tape and have some sort of  reflector holding a electric  radiant element above it to shine down in the belly surface. you would not neccesarilly have to keep he caul inside the heated area or have the assembly enclosed for that matter.

[simk]

[/quote]I actually like the mud idea mentioned above, clay is easy to get and easy to wash off.
[/quote]

Dont't try this without glasses and helmet! I did it some time ago and the wet clay sucessivly exploded in little pieces while I did heat treating...the little pieces are quite aggressive and hurt badly in the face. Something like mud is maybe the better opition...
Cheers