Tenbrook and I had a conversation about the effects of heat on TBIII glue. A few years ago I had called the TB folks to see how I could remove a damaged hickory backing I had glued with TBIII. They told me to heat the glue to 150deg(F) and the glue would release. I did and it did!
Well, Tenbrook called TB and asked about strengthening TBIII glue with heat treating. The answers we both got from TB seemed to contradict each other so Tenbrook called TB today and here is the PM he sent me. Tenbrook has only used the heat treating on risers so how it will work on backed bows or multi-lams will be interesting and hopefully helpful for our craft.
"Okay just got off the phone with titebond....Sounds like we are BOTH right.
TitebondIII deos soften at 150 degrees.
However when heated above 150 (160-180 degrees) then allowed to cool it activates a secondary cross-linking in the glue making it SUPER strong! After it has been heated to temps between 160-180 then allowed to cool it becomes so strong and impervious to heat it will not come apart when soaked in boiling water (they actually test for this).
Hope this helps and happy hunting!"
Tenbrook
neat! thanks for that.
I never use heat to remove a bad backing, just takes too long. I clamp the bow flat on the work bench and use a hand held belt sander. You have to be careful and go slow but I just sand the backing till I see the glue joint start to appear and then keep moving down the bow. Then I use a toothing plain to get the rest of the backing off and to smooth out the glue joint. I can have the old backing removed and the bow ready for a new backing in 10 minutes. To remove a riser, I band saw it off, staying 1/16th away from the belly of the bow, then use hand tools to get to the glue joint.
This is very interesting because I've used heat to correct twist and other tillering issues on wood lam bows glued with tbIII and have never had one fail. I guess the key is to make sure you keep it clamped up until it cools.
Hey, Pat your kind of guys are why I like this place, very interesting. Too darn bad the guys 10000 years ago didnt have the tech..... :clapper:
So I wonder if TB2 has the same properties??? thanks for the info guys! May have to cough up the extra for TB3 next time.
I just wanted to add... I don't know if TB3 will stay together in highly reflexed or recurved backed bows, tr-lams and such if heat is applied enough to bend the wood to make alignment corrections??? But I do know it works with Smooth On. I've done it with all-wood bamboo backed recurves and highly reflexed longbows... did it a few days ago to a d/r tri-lam with 5" of reflex. I actually heated the bottom limb and moved it 3 times before I had it just right. Had the bow held in the vice by the handle with weight hung from the limb tip, allowing gavity to pull the limb sideways while I heated it with the heat gun...
That's some awesome news. So a person could glue up a riser block with TB3 theoretically, then shape and cook the whole thing with the limbs using smooth-on? Might have to try that. Only catch I could think of was making sure the gluelines were effectively clamped and not in shear as it passes though the 150 degree "soft" zone.