glue, backings, sinew & such

[willie]

When it’s clamped down it’s not allowed to shrink. How about you soak it, stretch it. Measure it. Let it dry and measure again. THEN say it doesn’t do anything.
But it will shrink.

Of course, I prefer to say it shrivels, as it doesn't seem to exert much contraction force when it shrinks. Or at least, it did not take much to overcome the contraction in my experiment. Just being loosely stuck to the side of a roughly sawn WRC slat was all it took.

Any experiment you could undertake to quantify a contraction force would be welcomed.

[willie]

Baugh got a measurement of 3% for sinew shrinking.

 Again, it comes down to the matrix combination of materials.

Pat,
 Baughs test tendon was unrestrained. I believe your assertion that a matrix having it's own properties is right on, Its a new animal, just as crossing a coon hound and a poodle would make...... a mutt.

You need to measure the  shrinkage unrestrained or stuck to a material that can actually  be moved by the sinew shrinking.

 Sticking it to something that is stiffer than a strand of sinew has the power to move does not tell you much.

Yes my test was not very quantitative. A better test would be?

[PatM]

Secure a strand to s thin slat at either end and see if it reflexes the slat.   Or tack it to a couple of slim dowels pegged into a board and see if it draws them slower to together when drying.

  We also tend to reflex a stave rather than just applying sinew to a flat stave.  That allows the backing to start off effectively shorter even if it didn't shrink at all.

  Looking for another natural mixture seems a like a bit of wasted effort just because we don't know exactly how  something works. It's more important to know that it does.

[willie]

HoosierF

thanks for taking the time to share your experiments. Much food for thought.

Especially

5 - Sinew with Tite Bond II or Elmer’s Max.  I like these glues better than TB III for reasons i can’t explain. TB won’t magically pull a bow into reflex like hide glue but if you reverse string the bow while the glue is curing you won’t be able to tell the difference next to hide glue except by appearance and cure time. It still takes a week to 10 days to reach full potential.  Once the reflex cures in i find it to be indistinguishable from hide glue and sinew as long as you reverse string the bow to cure. If you don’t it does not perform as well as hide glue.

To me, your experience seems to indicate potential for some possibly lighter weight combos. Possibly with plant fibers?

You were getting results in a week to ten days? Makes me wonder what an extended cure time would do?

[simk]

What about horsetail hair with titebond, glued up in reflex?
Just thought about that latley as I read the "Human hair for bow belly"-thread / Probably somebody did already do it if it was a good idea.
Cheers

[PatM]

Extracted plant fibers are actually  heavy.  Also within a glue matrix they are really hard to glue so that they do not move and slip within the matrix.

 In essence a unidirectional plant fiber backing is an attempt to make a strip of bamboo.    Might as well use what's already there.

[willie]

Secure a strand to s thin slat at either end and see if it reflexes the slat.   Or tack it to a couple of slim dowels pegged into a board and see if it draws them slower to together when drying.

  We also tend to reflex a stave rather than just applying sinew to a flat stave.  That allows the backing to start off effectively shorter even if it didn't shrink at all.

  Looking for another natural mixture seems a like a bit of wasted effort just because we don't know exactly how  something works. It's more important to know that it does.

If we purposely reflex the stave before application of the matrix, it might be said that the benefits come from  just reflexing the stave as much as from the makeup of the sinew or hide glue it's self.

If you think experiments along this line are wasted effort, I guess you will not be testing any sinew as you suggest?

Extracted plant fibers are actually  heavy.  Also within a glue matrix they are really hard to glue so that they do not move and slip within the matrix.

 In essence a unidirectional plant fiber backing is an attempt to make a strip of bamboo.    Might as well use what's already there.

I see bamboo fiber on the yarn market. Perhaps suitable for bow designs that would be difficult with a bamboo slat?

[PatM]

Natural fibers generally need chemical treatment somewhere along the line to either extract them or really glue them well.  Often very complex and environmentally unfriendly.  Bamboo being one of the worst, if not the worst.

 Sinew, not so much.

[DC]

I see bamboo fiber on the yarn market. Perhaps suitable for bow designs that would be difficult with a bamboo slat?

Willie -I did a little investigating(not much) a while back and what I found says that the bamboo fiber is more like a rayon making process. It didn't seem to be actual fibers from the boo. I may be wrong.

[BowEd]

hoosierf.....Nice contributions of experiences you have about backings.Your an experimenter and that's good.I'm a user of combed flax myself to fix things on bows.
I'm wondering if you kept track of the amount or percentage of reflex that your sinewed bow kept after tillering and shot in done with TB II glue?You know there's a reason the asians don't use TB II with sinew on their horn bows.

[willie]

Don, now that I think about it, the fibers I was looking at looked pretty refined. One of the great Chinese inventions besides gunpowder, crossbows and the compass, was paper money printed on an improved bamboo paper. Interesting reading........

[PatM]

Also remember that reflex is often just pulled in on a sinewed bow by reverse bracing.  We do also tend to heat treat it in as well but it bears mentioning that it often is just the glued backing retaining the reflex, in which case it is responsible alone.

[Morgan]

I would love to know if shrinking sinew does in fact have enough force to pull or increase the reflex is a bow or if it is just the reflex put there at glue up.. I know that sinew shrinks as it dries, but so does rawhide.

[PatM]

Before people got into reverse bracing, sinew backing was well known to cause long term reflex acquisition.

[BowEd]

Morgan...the way I understand it and from experience here the make up and pattern of fibers of rawhide are different than sinew laid in line along a bows' back.Reason rawhide will stretch and not come back.It takes set.
Fibrous backings like linen or flax will do the same thing.They will take a set.
Sinew in conjuction with hide glue has a spring back action or resiliency that other backings don't.I'm speaking of more extreme reflex than put in with a wood backing.Wood will only stretch 1% so they say and I think it's true.In fact let a hide glued sinewed bow rest and you will see it go into reflex as it sets.One thing that amazed me about these composites.It's like they are alive even more so than a self bow.