Dry vs "seasoned" sinew

[PEARL DRUMS]

That very thought is what prompted me to start this thread Pat.

[paulsemp]

Another thing to think about.... 50% humidity at 30 deg is not the same as 50% humidity at 80 deg. Cold air does not hold moisture like hot air. So with that comparison at 30 deg the amount of water in the air would be much less.

[ionicmuffin]

No tests here Pat. But I check on my sinew jobs almost daily when I do one up. It seems to me if done in the proper season, after a week to ten days its hard as rock and cant be dented with a thumb nail. Not exactly scientific, I know!

Actually i think you are more scientific than you think, more observatory but thats one was to conduct science.

[Marc St Louis]

The difference I have found is that a bow that has had the sinew cured rather than just simply dried is more stable once finished tillered.  A bow that is tillered with just dried sinew will have the tiller change over time.

[Danzn Bar]

I only have attempted one sinew backed bow, and still working on it.  The osage stave was three years old and stayed in the house, with heat and air conditioning and we very seldom open windows.   I did the bow build in 17 to 25% RH and when it was time to sinew the RH was 18 - 20% the hole time.  After about a week I noticed stress cracks in the belly and it gained a little reflex.  After three weeks the bow had not gained any more reflex and the sinew/glue was hard as a rock.  Finished the tiller and now have shot it about 250 times. I have taken FD pictures after almost every shooting session and the tiller seams to be changing each time.

With only this one experience, I'm leaning towards Marc's comment.

The difference I have found is that a bow that has had the sinew cured rather than just simply dried is more stable once finished tillered.  A bow that is tillered with just dried sinew will have the tiller change over time.

I have not been doing anything to the tiller each time just shooting and hoping that the tiller will stay the same at some point then I guess I would do the final/finish tiller.  Maybe I should have waited a few more months.  Time might tell me on my first build and I can improve on the next and the next and the next.  Experience can tell the story........If you listen. 
DBar

[mullet]

The difference I have found is that a bow that has had the sinew cured rather than just simply dried is more stable once finished tillered.  A bow that is tillered with just dried sinew will have the tiller change over time.

I have had to retiller a friends sinew/osage bow twice over a 20 year period. It keeps gaining weight and he can't string it.

[PatM]

Sometimes the "weight gain" of a bow over 20 years is a loss of strength of the owner
 I think Marc  may be talking about going out of tiller rather than an increase in draw weight.

[Eric Garza]

Not to add more complexity to an already complex question, but another issue that underlies the dried versus seasoned sinew debate is how much glue there is in the sinew/glue matrix. It seems that if one were to add a lot more glue relative to sinew, the collagen in the glue might be oxidizing, polymerizing or chemically changing in some other fashion over a longer period of time, and it might absorb and release water at a different rate than the sinew and wood. On the other hand, if the bow maker added just barely enough glue to get the sinew fibers bonded to the wood and to each other, that would create a very different dynamic within the backing over time.

The sinew fibers might also change chemically over time, as there's non-fibrous (non-collagen) tissue within a tendon much like what people find within a deer hide and remove by bucking (soaking in an alkaline solution, usually wood ash) and then acidifying (soaking in an acid solution, usually diluted vinegar). Maybe there's value in letting some of these non-fibrous tissues degrade, leaving just the collagen? Come to think of it, has anyone ever tried treating sinew like a hide before using it to back a bow? As in bucking and then acidifying it so as to remove non-collagen tissues?

As someone who processes a lot of sinew, I've definitely noticed that back tendons that are dried and stored for a couple years are much easier to separate into individual fibers. I have some really long pieces I've been saving that are about 3 years old, and they have a different consistency and feel in the hand than the ones I cleaned and dried just this past fall. Does this mean they'll make a better bow backing? My instinct says yes, just because of how they feel, but I won't know that until I make otherwise identical bows and back one with old sinew and the other with new. I don't have two staves that could yield identical bows at the moment, so I'm not in a good position to do this experiment.

[PatM]

 The vast majority of dry tendon is collagen or elastin. Approaching 90%. The rest surely is barely worth getting rid of.  Washing the tendon well probably gets rid of any readily soluble stuff.
 I can't really see any point to adding extra glue.  Hard to see how that would add any better stretch/elastic quality.
 I reduce the glue in my backings to the absolute minimum.

[mikekeswick]

<snip>If not then I guess all we've got is that they did it in the past and logic tells you that they wouldn't have done it if there was no benefit. Bearing in mind that back when the Turkish were making these hornbows en masse the methods used would have been the ones perfected over many hundereds of years.

Uhmmm... actually logic tells us no such thing.  We could surmise that there may have been some reason for the this practice that was based upon scientific observations and sound engineering, but it certainly does not follow merely from the demands of logic that such was the case.  Any of a thousand explanations might explain the same behavior as well or better than the sound and reasonable engineering theory.  Magic, superstition, tradition, practical demands of mass production, or any number of other ideas could readily have caused the exact same practice.  I mean, it's farfetched, but it could even have been that there was a higher tax rate on finished bows than bows that were in the process of being made.  So perhaps they delayed finishing them till they had a buyer to pay the taxes.

The 7 most powerful words to blockade any kind of progress are "That's the way we've always done it."  Ancient peoples were not less subject to the power of those words than we are today.  In fact, I'd postulate that they were likely far more impeded by their power than are we.

Not all sunken chests have a bottom lined with gold doubloons, ...some just have old dead sailors wet socks in them.  Just because an idea is old and hidden in a veil of mystery, does NOT mean it is the best or better idea.  Logic certainly does not imply such.  Logic only tells us that there was a reason, and perhaps several reasons, but it does not require that the reasons were good ones.

OneBow

I have to say that you are missing my point rather...
Read Adam Karpowzi's book. Then do some research into the distances achieved by the Turkish flight archers. There are rather large stones planted in the ground at the place where the record distance arrows landed. They are still there!
925 yds is quite a shot.
When somebody comes close to that  again i'd like to talk to them!
I don't agree that the bowyers of old were stuck to the mentality of 'that's how it's always been done' Look at a Turkish bow and then tell me that that design was arrived at and then stuck to doggedly....If poeple were stuck in this way of thinking then NOTHING would ever be invented....
When did I say that sunken chests were full of dubloons?

[mikekeswick]

That's just it Mike. Lots of things done in the past don't hold nearly the water now. Im not arguing any points you've made, just conversing is all.

Ah but many more do than don't!

[mikekeswick]

We've learned from other experiences that wood dries at a rate of about 1" per year in general. I'm sure some woods dry faster than others. Has anyone done a test to see how long it takes sinew/hide glue to dry.

Look at my first answer on page 1   

[mikekeswick]

Sometimes the "weight gain" of a bow over 20 years is a loss of strength of the owner
 I think Marc  may be talking about going out of tiller rather than an increase in draw weight.

By definition they are the same thing?

[PEARL DRUMS]

After reading all this I feel fortunate than none of my sinewed bows have changed enough to notice, I only have 2 in my possession still, but haven't got any negative feedback on the others that are out and about. Not sure why Im the lucky one? Im starting to lean towards glue quality and QUANITY playing a huge roll. Also, Eric's spin on older sinew is the same as mine. I have some "Gus" sent me maybe 3 years ago? Its what I recently used on a yew bow and is like angel hair after some work. Also, I leave very little glue in the sinew. Just enough to stick down and blend in. I think 2 months is the longest Ive ever waited on sinew.

[blackhawk]

The difference I have found is that a bow that has had the sinew cured rather than just simply dried is more stable once finished tillered.  A bow that is tillered with just dried sinew will have the tiller change over time.

+1

All it took was once for me to find this out and learn my lesson..so I now wait...besides what's the rush? This isn't a race....better safe than sorry in my book,and just wait it out....

Screw sinew anyways,its overrated