cauls and fire hardening

[darinputman]

Fox, sorry but been busy. What Eric stated is true, the thing I was hoping to gain from fire hardening hickory was to be able to make a bow that wouldn't take on moisture as it was stored in high humidity environment. I was very impressed with how the  bows turned out but after leaving them in my shop for a few months they would gain moisture content back and would become sluggish. The good news is that a few days in the hot box and as they dried out the cast would come right back up.
   If you would like I can try and post some of the stats on how much speed was lost and gained back as well as moisture content changes on a few of the bows. May be a couple days though.

[darinputman]

Here is a picture of my caul and my firehardening setup. Also notice how dark the hickory can get and still make a good bow. For me the challenge was to keep the color consistent from fades to almost the tips. Wound up making my bed where my coals went follow the same  slope as my form.

[Fox]

Thanks, darinputman!! That's super helpful! you put a good bit of reflex in that! and really make it super dark... im going to heat mine this weekend, ill post picks when i do

[TimBo]

Darin, thanks for sharing all of your results it's super helpful.  How did you seal your bows? 

[darinputman]

Timbo I used the massey finish, I use denatured alcohol instead of acetone it gives me a little longer working time.
 For anyone not familar with the finish it's simply 2 part epoxy thinned down with acetone put on with several coats applied. It is the best finish I have ever used as far as sealing wood bows and arrows are concerned.

[Fox]

Okay I fire-hardened this hickory bow for 2 hours and the belly is mostly even but not perfect, and the back looks pretty dark. Is this too dark? did I kill it? If I back it with rawhide or something will it be alright?

[Fox]

Untitled by Livvydog, on FlickrUntitled by Livvydog, on Untitled by Livvydog, on Flickr

[darinputman]

What did you have your back sealed with did it have any color to it before heating or was it hickory white? Here's a picture of one of mine you can see the shellack bubbled up pretty good.
 

[darinputman]

It don't look scorched to me at all. But I'm just looking at the picture and kinda hard to tell. But by the color of the belly I'd say you got a good heat treat on it and go with it. But thats just my opinion and have broken 1 hickory due to a scorched back but it was a badly scorched knot and I wouldn't have backed it anyway.

[Fox]

I didn’t have it sealed with anything.. in the middle photo you can kinda see at the far tip of the bow what it looked like before the fire hardening… it’s definitely pretty brown now..

Thanks for all the help darinputman

[darinputman]

Fox, I would have expected that wood to have checked since the back was not sealed being heated for 2 hours, which is about what I heat mine for + or - a few minutes. I would look it over for checks really good if you aint already. Hope all goes well and put some pictures of finished bow on here please.

[bownarra]

Yes that is why heat treating should only be done on very dry staves.
That back looks toasted to me....if you do it right then the back shouldn't change colour. The heat is hitting your the face of your form and 'collecting' inbetween the form and the back. Forms should be narrower than the stave and then you won't ever have a problem.
hickory may be able to handle the compromised back but most woods won't.

[BowEd]

I heat treat with a gun but thoroughly.Being sure wood is dry.Shellacked backs come off form stuck to the form as the shellack on the back bubbles up and reliquifies too.Dark brown is my preferred color.Matching forms.One narrower than the other to let hot air blow by.I've found using actual aluminum heat ducting tape stuck to the back on the bow limb on forms wider than bow limbs while heat treating keeps the back from getting a burnt color. It can take heat up to 600 degrees F.Once used though it can't be reused very easily.