Sinew pulling off growth ring/pics added

[DuBois]

I sinewed an osage bow 2 weeks ago and now there are 8 spots along the edges that are pulling away from the wood and look like they have a little wood along with the sinew. Maybe 1/16" at most and 1 to 4 inches long each. Is this a lost cause. hardly able to close gaps with clamping so not sure what to do. Luckily it is hide glue so could salvage sinew.

[Pat B]

Marco, will you post pics of where the sinew is lifting.
 You may be able to use a little heat and more glue to reglue those areas but without seeing it it is hard to tell.

[JW_Halverson]

It is sounding dubious, DuBois-dude.  Try to get some good close up photos of the affected areas like pat recommended. I would very much like to be wrong on my first impressions. Got fingers crossed for you.

[Mesophilic]

I sinewed an osage bow 2 weeks ago and now there are 8 spots along the edges that are pulling away from the wood and look like they have a little wood along with the sinew. Maybe 1/16" at most and 1 to 4 inches long each. Is this a lost cause. hardly able to close gaps with clamping so not sure what to do. Luckily it is hide glue so could salvage sinew.

What part of the country do you live in?  I ask because I've had this same problem on several sinew backed bow attempts.  And I'm curious to find a solution.   In my case, it pulls up alot of wood as it cracks.

I've attributed it to my high elevation and extremely low humidity but have no way to know for sure.  When I  lived in Ohio I never had s problem,  nor when I lived in Arizona even though the humidity was low,  but I was at a much lower elevation.

I've repaired on section only to find it spreading.   I've even heard the wood snap and crackle,  run over  to check snd sure enough, rings pulling apart by the sinew.

So far the only wood the sinew doesn't pull apart on me is hickory.

I may try something I read in an older book in which thd author used a technique ov gluing rawhide on the belly  and sides.  After the sinews cured he sanded off the rawhide.

[bradsmith2010]

that is extremely interesting,,
i dont have experience with that and am only guessing and spit balling,,
could it have to do with the way the back was prepped,, before putting on the sinew,,,
but pics would be great,,
I sinew in high altitude and low humidity in Santa Fe,,, and have had more issues than at sea level, but not sure if that was really the reason,,

[DC]

How wide is the bow? I seem to remember something on here about wider sinew bows shrinking in width and ripping up the edges.

[DuBois]

Hey JW 
I lost my old phone which became my camera since  cant get the new one to load photos into computer. I'll get some pics as soon as can but I'm gonna write this one up as lost so put your fingers to use in some other way.

Diesel, I'm in Minnesota and it's cold so very low humidity outside but we have a humidified furnace set at around 50%. That said, I  have been burning wood stove a lot and bow has been downstairs in next room from stove so maybe less  humid in that spot. Just realized as I write that there's no air vent in that utility room.

DC, bow is 1 and 1/8" at widest

[bradsmith2010]

Jay Massey preferred hickory and sinew, maybe thats why,,
also, did the sinew go over the edges,, I think that might help,,

[DuBois]

I don't think I went over edges enough. I've had this happen once before and I think I hadn't gone over edges then either but I'm not 100% sure on that.

[DC]

Is it pulling apart between rings, like maybe the early wood is failing.

[willie]

if you decide to salvage the sinew and abandon the stave, it might be instructional to see if the sinew is case hardening any, ie drying too fast on the outside.  perhaps you can peel it off rather than soak it off to see?

outside humidity in minneaplolis is 66% right now, the air only gets "dry" once you heat it, or to be more accurate, the absolute moisture content does not change, just the relative-to-temprature capability.

not suggesting you give up on it, but put it in an unheated space until it gets warmer outside might be a good idea

[DC]

Does sinew shrink more or less depending on drying conditions? Put another way will sinew shrink more if it is dried faster? I would think that dry sinew would be dry sinew.

[PatM]

Sounds like it's pulling the growth rings apart.  If you go over the sides it seems like you'd just potentially move the  area of potential separation down another growth ring or two.

 I have had "tri-lam" bows using sinew as the outer layer pull the wood core from the belly as they cured.  I solved that by pre-curing the  sinew and  core and then gluing that to the belly.  Not really an option for you.

 When you sinew back a backing strip and observe how the belly side drastically changes shape from wet to dry and cured it's no wonder sinewed bows can separate.

[bradsmith2010]

well maybe its not anything you did,, or did not do,, it might just be the material was not up to the strain,, sometimes a stave will de laminate for no reason,, it could just be the wood,,hard to figure,,

[maitus]

I agree with bradsmith2010. Common problem usually is the delamination of sinew. But if the sinew tears the wood apart, it must be a low quality of stave.