Sinew lifting off Osage

[Black Moshannon]

I'm posting this for a bow making friend who isn't on this site. This is an Osage bow he made last year and sinew backed with hide glue. Now some of the sinew is lifting off. He recently drew it and a popping sound was heard and a flake of sinew lifted off. Any recommendations how to fix? Here's some photos

[PatM]

Something was amiss during the process.  It will need being redone to be sure.

[bownarra]

Yes people might ay flood it with thin glue....only worth doing if you absolutely know the rest of the backing was laid down correctly....
Personally I'd remove the sinew and put it on following this.
Warm the stave and size with 5% glue. Do this until the back is glossy.
Use 25 - 30% glue for the first layer. Then 20% for the rest.
Sinew must be laid onto a warm surface so the glue isn't close to gelling for a proper bond. A lot of people try to sinew when it is too cold.

[Pat B]

I'd say to remove the sinew and properly prep the back before adding sinew again. You can probably soak and separate the sinew and reuse it.
 I would sand the cleaned back, brush off the dust with a stiff brush, wash the back with Dawn and rinse with boiling water then go right to adding the new sinew back by sizing the back well first before adding the sinew.

[Black Moshannon]

Ok thanks. He is going to remove it. What is the best way to remove sinew? I would have guessed to put rags of hot water on the back. There are tip overlays held on with hide glue too.

[Pat B]

He might try lifting it at the tip and peeling it off in one long sheet. That worked on one of mine years ago. If that doesn't work he will probably have to rehydrate it to remove it but that isn't as easy as it sounds.

[Badger]

   The first osage bow I sinewed all the sinew pulled cleanly off. I use a little courser sandpaper on it now around 80 grit.

[bradsmith2010]

I usually just take a knife and scrape it off, careful not to damage the back,,

[bownarra]

Collagen based glue bonds best to a smooth surface. No need to try and degrease if you size correctly.

[BowEd]

Starting over here with the advice given will get you there.Although I'm not one to sinew much osage myself.
The white woods seem to need help getting up to the standard of osage sometimes.
Sinewing in a warm enough enviornment after sizing well to be sure layers are properly adhered to each other.
I would save the scrapings of old sinew and glue though.

[bassman211]

80 grit sand paper is not a smooth surface. Nor is   taking a fine tooth hack saw blade to the bow's back before laying sinew on it. Many of us have been successful doing it both ways . When you glue a horn belly to the belly wood are both surfaces smooth? I have seen guys cutting grooves in the horn before the glue up, and the the bow's back. I am confused. Are their different ways to do it with same end result?

[BowEd]

The grooving is'nt really making the surface rough as the grooves are smooth too.It's makng more serviceable glueing area.
Needed more on very high poundage bows.
Same but to a lesser degree with toothing lines with a hacksaw.
Sanding overall to make the surface rougher is a different thing.
It's best glueing according to the glues' reccomended surfaces,and yes I have grooved and glued a few horn bellied bows myself.
Again while doing this keeping your environment warmer to give you time to wrap everything tightly.

[bassman211]

Ok, Bow Ed the reason I asked is that I have sinew  backed a good many bows, and so far have never had a problem with any of them. I believe the fine toothed hack saw  blade deal was from here. To  be honest with you I have never did it any other way. Most of the Osage, and other bows that I have sinew backed had violated  backs of one form ,or another.

[bradsmith2010]

Jim Hamm taught me to rough the back,, so thats the way I always did it,,,I have had a few failures,, I am sure there are other ways,, I once read a  book claiming putting sand in between the layers was the best way to do it,, 

[PatM]

There is clearly no one right way to sinew.
 
 There's no one wrong way either.