Author Topic: Hide glue for backings - An experiment  (Read 6482 times)

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Offline sleek

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Re: Hide glue for backings - An experiment
« Reply #15 on: October 16, 2019, 04:11:45 pm »
ok you guys knew this was coming,, which one is gonna shoot faster,, I mean more effeciently (lol)

Probably a tie. consider how light the tight blond is.
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Offline Halfbow

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Re: Hide glue for backings - An experiment
« Reply #16 on: October 16, 2019, 04:47:21 pm »
Dick Baugh did some testing on this.  Interesting read.  You can Google  "Secrets of Sinew Revealed" with his name.

Thanks, an interesting read indeed. But his main conclusion seems to be to use hide glue because it shrinks and pulls the bow in to reflex. I don't see why you couldn't get all the benefits of that by just manually inducing reflex during glue-up with a different glue. I don't see anything special about getting reflex from shrinking glue vs getting it from a backwards braced bow. Just different ways of getting the same reflex.

What I'm talking about has much more to do with the hardness and springiness of the cured glue. (Like you were saying Sleek)

ok you guys knew this was coming,, which one is gonna shoot faster,, I mean more effeciently (lol)

In the context of a bow backing, I'm not sure. But I will say this. If I took my two flax twigs and strung them up, making tiny bows with terrible tillers, I'm certain the hide glue bow would've made a decent toy. It would've confidently shot a tiny arrow across the room. The Titebond one.. I imagine that when I released, the arrow would just fall to my feet. So though the hide glue is heavier, it seems much more able to carry its own weight than the Titebond.

Offline willie

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Re: Hide glue for backings - An experiment
« Reply #17 on: October 16, 2019, 05:30:05 pm »
http://www.primitivearcher.com/smf/index.php/topic,63182.0.html

has some discussions about hide glue. related to this thread, I dried some strands of sinew with out glue, and they did not shrink much when mildly restrained. If glue/sinew matrix shrinks, but the sinew by itself, not so much, then I am not sure that having a stave pulled into reflex by drying is all that beneficial. This is not to say that having reflex does not help a design, but only to support your Idea that how you obtain the reflex may not matter much.

Offline SLIMBOB

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Re: Hide glue for backings - An experiment
« Reply #18 on: October 16, 2019, 06:30:25 pm »
I believe that shrinkage is the main benefit. If you use a PVA glue the sinew still shrinks, but the glue does not. That means some of the sinews potential is used up pulling on the glue. With hide glue it is pulling the bow into reflex along with the sinew. That, coupled with the sinews ability to stretch without breaking is the “secret” so far as I am concerned.
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Offline willie

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Re: Hide glue for backings - An experiment
« Reply #19 on: October 16, 2019, 07:50:41 pm »
Slim,
 are you saying you have tried the titebond/sinew combo and the bow was pulled into reflex by the matrix(or possibly the sinew acting alone)?

Offline SLIMBOB

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Re: Hide glue for backings - An experiment
« Reply #20 on: October 16, 2019, 08:16:27 pm »
No, I never have. I simply know a lot of people who have done it with PVA glue and none have said the results were as good as hide glue. When you question why, and look at the available research, what little there is, that appears to me to be the most reasonable conclusion.
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Offline willie

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Re: Hide glue for backings - An experiment
« Reply #21 on: October 16, 2019, 08:32:45 pm »
reported results cannot be argued with Slim, Thanks


Offline SLIMBOB

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Re: Hide glue for backings - An experiment
« Reply #22 on: October 16, 2019, 08:41:14 pm »
Not sure I follow...
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Offline Halfbow

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Re: Hide glue for backings - An experiment
« Reply #23 on: October 16, 2019, 09:16:50 pm »
I believe that shrinkage is the main benefit. If you use a PVA glue the sinew still shrinks, but the glue does not. That means some of the sinews potential is used up pulling on the glue. With hide glue it is pulling the bow into reflex along with the sinew. That, coupled with the sinews ability to stretch without breaking is the “secret” so far as I am concerned.

If you reverse brace a bow, you are compressing the wood on the back of the bow, shortening the back. Then you glue your backing on to this shortened back. Then when you remove the string that was bracing it, the wood tries to return to its original position, tries to lengthen the back. But the new backing stops it from going far, reflex is held. The backing (sinew and glue alike) gets tensioned by the wood trying to return, no shrinkage necessary. If, while drying, the sinew does shrink without the glue, the only potential that gets "used up" is potential to pull the bow in to reflex. Which you don't need because you've done it with muscles and a string. As long as everything adheres and dries properly, the end result seems very similar to getting reflex by shrinkage. In both, you end up with a backing that in some sense is too short for the bow. If do this with both methods on clone bows and you make the amount of held reflex identical, then the amount of pre-tension on the back must be identical. You can tell because it's pulling the wood in the same way.

I'm genuinely curious, did the people you know who tried it with PVA manually induce the same amount of reflex that hide glue would've pulled the bow in to?

If there is a performance difference even with the same amount of reflex, I feel like the difference that my test here highlights is probably the real consequential difference between glues.

Offline SLIMBOB

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Re: Hide glue for backings - An experiment
« Reply #24 on: October 16, 2019, 10:07:09 pm »
This is just as I understand and interpret things...if the sinew shrinks upon drying, and will pull the bow into reflex of some degree, and the hide glue shrinks at the same rate further pulling the bow into reflex. And we see that the PVA glue does not shrink significantly upon drying, then the shrinking sinew is pulling on the non shrinking glue. This will be true regardless of how much reflex you bend in, so some of the sinews potential is being lost unlike when using hide glue. Again this is just as I have come to understand it.
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Offline bradsmith2010

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Re: Hide glue for backings - An experiment
« Reply #25 on: October 17, 2019, 12:39:28 pm »
If u made two bows,,,used same amount of sinew,..put same reflex,..one bow might hold the reflex better,.depending on the glue...giving it better performance

Offline Pat B

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Re: Hide glue for backings - An experiment
« Reply #26 on: October 17, 2019, 01:49:34 pm »
I've used TBIII over a sinew backing for waterproofing but never used it as the glue for a sinew backed bow. I know folks that have and are happy with the results but for me it hide glue for sinew.  :OK
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Offline Halfbow

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Re: Hide glue for backings - An experiment
« Reply #27 on: October 17, 2019, 03:00:02 pm »
If u made two bows,,,used same amount of sinew,..put same reflex,..one bow might hold the reflex better,.depending on the glue...giving it better performance

Definitely. I figure it's usually possible to get the same reflex to hold initially with the necessary know-how, but if one glue loses it faster over time/use I want to know about that. I suspect that might indeed be the case.

Hide glue for me too. But not just for sinew. My test has me thinking it's better for plant fiber and such too.

Offline willie

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Re: Hide glue for backings - An experiment
« Reply #28 on: October 17, 2019, 04:31:41 pm »
Slim,I am just saying that test results are more substantial than speculations.

Two thoughts come to mind Halfbow.

when experimenting, consider that the amount of shrinkage of most things that dry is directly related to how much water is evaporated,

and plant fibers typically have very little stretch compared to sinew/glue. there are exceptions and yarns (twisted fiber) have more stretch than straight fiber

Offline SLIMBOB

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Re: Hide glue for backings - An experiment
« Reply #29 on: October 17, 2019, 05:15:31 pm »
Gotcha. So much of this is by feel for me. Almost all of it really. I appreciate the the testing that others have done and rely on it, if it matches up with what I have experienced. My rule is that if a test or pole or data tends to defy common sense, I cast it aside. The hide glue vs PVA glue...common sense leads me to accept that hide glue is preferable with sinew. I am open to another possibility.
Liberty, In God We Trust, E Pluribus Unum.  Distinctly American Values.