Durable, waterproof sinew backing

[kevinsmith5]

Once again as part of my "horsebow without horn so you don't get to use glass" argument I'm looking for experience folks have with doing a sinew backed bow where the sinew was both waterproof and the bow was durable. The more ways, more examples the merrier. As an ELB guy and only so far making Flatbows for kids I've no experience with sinew, so if the answer is "can't be done" feel free to say so.

[Pat B]

You will never completely moisture proof any wood bow, sinew backed or not. I use Tru-Oil on all my bows and get good protection from it., plus it is easy to repair if necessary. My sinew backed bows will get mushy in humid, moist weather. When the humidity is high I don't use these bows and keep them stored in a dry location. 

[PatM]

Birchbark with Epoxy on top of the bark.

[Pat B]

I do usually use snakeskin or rawhide over the sinew  then seal over them.

[Blaflair2]

That's sweet pat, kool look to the bark

[kevinsmith5]

Could you just epoxy over the sinew? Do all of you glue the sinew down originally with hide glue?

[PatM]

Yes, you can just Epoxy over sinew. That's the method Jay Massey used. Massey diluted his Epoxy considerably before application but that's unnecessary and you'll get even better waterproofing by omitting the dilution except for a couple of drops of lacquer thinner.
 If you want your sinew to do real work, you'll use a collagen based glue.

[Pat B]

I've used Knox for sinew but with mixed results. Now I only use hide glue.

[PatM]

What could possibly go wrong with Knox?

[Eric Garza]

I've always thought that Knox was just purified, powdered hide glue.

At any rate, I usually save all of my finely shredded sinew scraps and make glue with them on the spot by warming them in a small amount of water when it's time to back a bow. That way the sinew (or hide) glue isn't heated multiple times, which I think reduces its strength.

[Pat B]

Pat, I had the sinew lift from the limb on two bows when I used Knox. It could have been my screw-up but I switched to hide glue and haven't had a failure or sinew lift since.

[Fred Arnold]

For you that save the hide glue for later use, can it just be refrigerated or do you need to freeze it?
I processed some  lately from my sinew and rawhide scraps and put in a covered plastic container in the fridge.

[akswift]

The birchbark with epoxy looks very nice.

  But I have to ask, are you speaking about the performance of sinew

If you want your sinew to do real work, you'll use a collagen based glue.

if so, why do you think epoxy is inferior?

[PatM]

Nobody suggested actually backing the bow with sinew and epoxy.  The reference was to PVA type glues.

[Thesquirrelslinger]

well, hide glue and sinew are chemically identical. so you get an incredibly strong, tough, close bond.
Hide glue is collegen.  Sinew is collogen. Both soften in water. epoxy just so happens to be hydrophobic.