When to put rawhide over sinew?

[BrokenArrow]

I have sinew backed a osage orange bow and I am close to getting a string on it.
Question: When should I apply the rawhide over the sinew? Now or when it has been tillered?
Thanks

[PEARL DRUMS]

Why a rawhide backing over sinew? 

[simson]

What Pearlie said, only adds mass !

[PEARL DRUMS]

I suppose I should answer your question. If your intent was to add rawhide from the start then it should have been added before you started tillering. When the sinew is dry and ready to go, add the rawhide, wait 5-6 days and tiller the bow. I say wait at least 5-6 days because adding wet rawhide to a self bow isn't quite the same as adding it to a sinew backed bow. The sinew will suck up that water like a sponge and will require more time to dry than a self bow does.

[Pat B]

What Pearlie said. This would also be for snake or fish skins, etc.
 I wait at least a few days before stressing a bow after adding skins to a selfbow, even oily wood like osage. I did this once and the weight dropped from 60# to 45#. After 4 to 5 days the weight was back up to 60#. It added just enough moisture to the wood(osage in this case) to drop the weight. Once dry again the weight went back up.

[BrokenArrow]

I thought the rawhide would cover up the sinew as it is not smooth. Am I missing something here?
I'm not a fan of snake skins but do not like the rough look of sinew either.
I like painted rawhide but what is the alternative?

[PatM]

   Rawhide won't smooth out rough sinew unless you intend to add tons of glue to fill in all the low spots.

 The solution is smooth sinew first and then any thin covering material can be used as a waterproofing layer.

[PEARL DRUMS]

One of the hot shot bowyers mixes up sawdust and TB3 as a bondo and fills in all the gaps and crevices prior to adding rawhide. I wouldn't advocate that.

[bradsmith2010]

a very thin rawhide,, deer,, wont add enough mass to hurt the performance,, or goat,,,, if you like the look of it... or want to paint it ,( pen and ink looks very nice on rawhide), it will help protect the sinew in harsh conditions just like a snake skin,, I have a bow I am planning putting rawhide on,, yes it will add mass but very little,,,, if you shoot a bow through a chrono, before and after,, you will see it is a very small difference if any,,, I made a bow for a friend last year, shot it through a chrono,, then put rawhide on the belly to cover some rasp marks,, I didnt want to loose weight by taking them off,,the bow shot the same fps after putting on the rawhide,, I had read about putting rawhide on the belly in a book AMERICAN INDIAN ARCHERY by Reginald Laubin,, he talks about putting rawhide on the belly of sinew bows to reduce checking on the belly of heavily sinewed bows,,anyway I guess my point is,,, rawhide does make a beautiful backing and with a good finish would protect your sinew back,,  if you are worried about the performance, then narrow your tips,, reduce the string count in your string,, or shoot a fast flight,,instead of b 50,,,or draw the bow 1/2 inch more ,, work on your release and it will shoot harder than before you applied the rawhide ,,

[Pat B]

You can paint over the sinew with acrylic craft paint to disguise the sinew but it won't smooth out the surface.
 

[looper]

One of the hot shot bowyers mixes up sawdust and TB3 as a bondo and fills in all the gaps and crevices prior to adding rawhide. I wouldn't advocate that.

What's your reasoning behind that opinion? Aesthetic reasons or performance degradation?

[PEARL DRUMS]

One of the hot shot bowyers mixes up sawdust and TB3 as a bondo and fills in all the gaps and crevices prior to adding rawhide. I wouldn't advocate that.

What's your reasoning behind that opinion? Aesthetic reasons or performance degradation?

Adding a 1/4 cup of glue and sawdust to each limb seems counter productive to me.

[Limbit]

Bradsmith, that's a lot of excellent advice! I recently made a mulberry paddlebow and did a light rawhide backing over the sinew so it would be easier to paint and the colors would be more apparent. Shoots great and looks great. I've heard you don't want to destroy the outer layer of sinew by sanding it as this is the layer doing the most work. I tend to agree with the concept especially for shorter bows where the sinew is really a contributing factor to its performance. So, in this regard, best to leave it be and just paint it perhaps.

[bradsmith2010]

well you could paint it and lightly sand it,before adding art work,,,, and it would smooth it out somewhat ,, I have put a pretty thick coat of paint on sinew back hunting bows that were expected to hold up in the rain,, as far as putting sawdust and glue on the sinew I cant really see any reason to do that,, you are trying to use the minimum amount of hide glue in the first place to reduce mass,,
I guess if your main concern was appearance you could do it ,, but I would think it would slow the bow down or reduce performance,, I have never tried that so I am just guessing

[looper]

I'm working on a couple of sinew bows right now and used the method that Ed Scott used. The amount of glue/sawdust it actually takes is nowhere near the 1/4 cup I mixed up, especially after it is sanded down.  I couldn't tell you the weight of the filler, but I doubt it'd be more than an ounce. If you don't use a filler of some sort and plan on using a backing (rawhide or skins), it would be very difficult, if not impossible, to not have any voids underneath the backing, at least the way I've been doing it.

If you want to leave the sinew exposed, you have to be really careful with applying the finish, making sure to completely fill all of the cracks and crevasses. You still have a pretty high probability of not getting it all of the sinew coated, and that is a recipe for failure, especially if you use hide glue.

As far as degraded performance, I doubt it'd be noticeable. My sinewed and backed bows are really good shooters, and although they have a little more mass weight than my self bows, they shoot harder, draw weights being the same.