Sinew Processes ?

[BowEd]

Truth is I've used the Fredrix type rabbit hide glue many times.It's never failed me.With excellent results witnessed through the chronograph.I'm not a name dropper but it's been used by someone else everybody who's been on PA forum for a while knows,but I'd have to agree hard to beat Knox too.Just as easy and available.
Nothing like making your own knowing what's going in it.

[gfugal]

Apparently at the strand level the sinew of all species is very similar. Variation seems to be more at the cross linking level  which everyone wants to break down anyway. There was a lengthy discussion on this subject on Paleoplanet a while back.

All sinew is made from the same stuff, this is true. When sinew increases in strength i'm not quite sure what is actually going on. Do you have a link to that paleo discussion? I think that would be interesting. I'm not sure if its just more collegen fibers connected together or something else as well. It can't be just the connections holding them together since that wouldn't increase the longitudinal strength. If it is simply more fibers then it doesn't really matter, because we break them down anyway like you said. However, according to the sources on wikapedia its not just strength that can change but the stiffness too. That can't be accounted for by simply making more fibers.

The mechanical properties of tendons vary widely, as they are matched to the functional requirements of the tendon. The energy storing tendons tend to be more elastic, or less stiff, so they can more easily store energy, whilst the stiffer positional tendons tend to be a little more viscoelastic, and less elastic, so they can provide finer control of movement. A typical energy storing tendon [the achelies for example] will fail at around 12-15% strain, and a stress in the region of 100-150 MPa, although some tendons are notably more extensible than this, for example the superficial digital flexor in the horse, which stretches in excess of 20% when galloping. Positional tendons can fail at strains as low as 6-8%, but can have moduli in the region of 700-1000 MPa.

What's interesting to note is the ranges. The non energy storing tendons are still much more elastic than wood (which is about 1%) so the strength really is a non-issue. What matters more is the stiffness. Surprisingly these sources are saying tendon is much less stiff than what other sources were saying. Much less. But it is intersting to note that non storage tendons are stiffer. That makes me wonder if backstraps are stiffer. This varability in stiffness indicates there is something other than the number of fibers. The only thing i was able to decifer was in these quotes:

The mechanical properties of the tendon are dependent on the collagen fiber diameter and orientation.

mechanical loading has also been shown to stimulate fibroblast proliferation and collagen synthesis along with collagen realignment

the mention of realignment and orientation suggests to me that these are factors that account for verying stiffness. And its not just between different tendon types but as i mentioned earlier, training (specifically jumping and sprinting) leads to stiffer tendons aswel. This is known to occure, I specifically remember reading about it the the book Sports Genes, which was a required reading for a class in my major.

[PatM]

Don't  lose sight of the fact that we use dried tendons. Surely that changes the  observations  done on living specimens.

With sinew backing I really think you have to consider your end matrix a whole new substance.

[willie]

Can anyone share what they have learned about differences between working times for the various glues mentioned?
fish
sinew
first pour
second pour
hide
bone (knox)

[Stick Bender]

Sense were speculating why, I was googling different aspects of animal glue particularly fish & Rabbit but I was thinking strength wise maybe it has to do with how pourious the different types of tendon sinew & how it's processed thin combed Ect are ,and the glue used, if a tendon is able to absorb more moister glue/water and the glue used is a slow gelling type (fish)  & the matrix is able to stay as plasticized as long as possible allowing allowing the carbon molecules to wiggle in place maybe increases the strength at a molecular level sense the strength springiness is a composite of time ,material & glue Ect , the ancients  new to keep the composite as placid as long as possible the Korean bows where made in the winter months to keep it placid as long as possible with out spoilage & long cure times some of those bows after hundreds of years the sinew strands where almost undetectable when dissected ,it was so complete as a matrix , I often think those ancients didn't have google & iMacs but there life's & there family's life's depended on producing quality products there is a reason why they did things the way they did ! I think maybe your right Aaron H 

[bradsmith2010]

ok Its getting over my head ,, whew,, seems the slow cure is effective, thats awful, cause I hate to wait on that stuff,, every time I think i am getting patient, theres a new issue to be more patient,,

[Stick Bender]

I trying a exsperment today Brad to really slow it down per time Baker Im adding organic vinegar to the Rabbit glue trying to make liquid hide glue also out hitting some of the asian store trying to find fish bladders , Patients is a virtue remember 

[BowEd]

Brad....For self bows cutting these fine lines I don't worry but for horn bows???Making enough of them with success and failure usually tells the tale.If things hold together good if not have to relook at how it's done or materials used.Contamination can be one of the main reasons for failure too.Grease/oil/dust etc.

[Stick Bender]

Maybe I'm getting a little over the top on my quest but what I'm after is nothing more then extending the gel time on the glue so I can get a picture perfect looking sinew job that's strong & no sanding needed when done & all strands meshed together before gelling ,when I have used commercial grade liquad hide glue in the past it was easy to obtain that but you hade to track down a fresh batch from the manufacture & test prior to use I think I have found the solution will publish later !

[PatM]

You are likely weakening the end result by adding stuff.

[Stick Bender]

I'm using nitrogen Pat most of it evaporates as the joint cures and what's left is fairly inert the strength can be adjusted threw viscosity but I'm using it at such low concentration  it probably won't make a difference but I'm running test on it now also going to try it with Knox , that's why I'm taking the action to test it rather then just assume it before using it ! 

[willie]

seems the slow cure is effective, thats awful, cause I hate to wait on that stuff

is gel time and cure time related? I thought gelling went hand in hand with temperature, and cure would be the long term drying that might be more dependent on humidity?

[Stick Bender]

I spent a good part of the week end exspermenting with glue looking for extending the gel time on rabbit skin glue , I reread Tim Bakers chapter on glue in TBB 1 so I thought I would start by trying adding vinegar  to the mix trying to exstend the gel time of hot glue I got up to 62% vinegar to the liquid portion per volume of the mix it failed never could get it to extend the gel time ,the glue acted the same as with water , next after reading articles on 17th century furniture makers to modern musical instruments repair & manufacturing it was interesting stuff really, I found out about adding urea(nitrogen ) to the glue commercial liquid hide glue manufacturers add up to 25% by weight to glue to keep it liquid so I got a hold of some commercial grade 45-0-0 urea  and starting by adding 2% by dry glue weight of urea it did slow it some but wasn't what I wanted so I worked my way up to 5% Urea , Bingo it was what I was working for ,as a test I re sawed a peace of osage I didn't degreased it or size it intentionally I took the amount of sinew that I would normally put down as a bundle and soaked it in water for 1/2 hour took it out squeezed it out swished it into the 118 Deg glue and purposely squeezed out a lot more glue then I would normally do I wanted the glue up to be weaker then normal after laying the bundle & flatting it out I was able to adjust the bundle for a full 14 min. at 72 Deg's  after that the glue would start soft gelling I could probably extend that at higher room Temp. I was able to get the strands down paper flat & strait , I'm going to do a bend & break test after 2 weeks cure to see I will post it then. This is not a formula for liquid hide glue but if you up the amount of urea it probably would be ,the formula I ended up with by weight for the viscosity I wanted was  glue to water ratio of 1 to 1.5 + 5% 45-0-0 Urea of glue weight , I added the Urea after the glue/water was well mixed & hot and re heated after urea to 118 Deg before use .

[PatM]

That's what the "old brown glue" commercial brand is....

[Stick Bender]

Yep I think most of those liquid hide glue manufacturers use it but in much higher concentration & I think they use standard hide glue that's 192 gram/strength  this glue is setting around 251 so even if the urea degrades it to 245 it's still stronger then regular hide glue but it really doesn't make a difference 192 TG will pull wood off before the glue breaks  I'm going to try it next with Knox