"How to" Sinew & Glue

[Keenan]

As requested by Semo, Here is a quick thread about sinew prep, from dried sinew, to applied to the bow.
First the sinew is cleaned of all meat and then layed out to dry untill it is hard and semi transparent. When dried it needs to be pounded lightly to break loose the casing and loosen the fibers. I use my anvil and a small flat faced hammer, but any fat surface will work. As the sinew is "lightly" pounded,roll the sinew, hitting all the way around to keep it from becoming flat. The outer casing will then loosen slightly when done.
 
 
 Then you can start to seperate the fibers keeping them as straight as possible
 
 
Place the fibers in small bundles of the same length.
 
Note: What you see here is about half the sine used for this bow.
 
Save the casings and small unusable pieces of sinew for the glue. This is one of about 6  or 7 small piles that I had left over from this sinew batch. Then place them in a crock pot with the pot about half full of water. This will make your glue. Cook with lid on for several hours until the water is very opaque and like runny syrup.
 
 
[IMG]

[Keenan]

Then after glue is cooked, strain into a container. This can be used immediatly or froze until ready to use.
 I use an old skillet on the wood stove to keep the glue warmw hile sinewing a bow. The glue should be very warm but not to hot to touch. At this point you will want to "size" the bow back. To do this simply wipe down the whole back of the bow with sinew glue. I always rough the back of the bow with course sand paper before this step. Some people use a toothing plane. Then I place a few sinew bundles in to soften.
 
 
After the sinew is very soft and pliable, I squeeze the sinew between my thumb and forfinger down the length to flatten and strain off excess glue. I dip it back into the glue and do this several times to help straighten the fibers. When the fibers are all laying flat and uniform I them apply them to the bow,starting at the end and rolling over the tip slightly.
 
It is impportant to always overlap the sinew bundles slightly when applying and try to avoid having the bundles all end in the same place. Similar to laying bricks.
 
 After the entire bow is sinewed. I place it in a vice on the handle and brace the limbs in a slight reflex, to help the sinew when shrinking.
The bow will remain like this for several days to let the sinew cure.
 

[Pat B]

Thanks Keenan. This is timely for me with my "Elkie" project. Do you clean the back first with a solvent or anything to remove oils or hand oil? My re-sinew job on Elkie has lifted in the middle of one limb. I though I had cleaned it well before I started sinewing but I guess not good enough. I'm going to soak the sinew off and start over.

[Walt Francis]

Pat, did you use leg or back sinew on Elkie?  I haven’t had any problems, but have heard of some people having problems with back sinew when the didn’t degrease or remove all the fat from it.

[KellyG]

This is going to be ever informitive here.

[Keenan]

Pat, with the Yew or Juniper, I have never had problems sticking. It's not oily like Osage. Hand oils could be a problem I guess, but I always sand just prior to the glue going on. I think the sinew glue tends to penetrate better then the gelatin glues.

[Pat B]

Thanks, I'll start another post as not to disturb this informative sinew-along! Good work Keenan. Looking forward to more!

[Curt Brisky]

Last week a friend emailed me about sinewing to ask if I ever soak the whole tendon and then peel the sheath instead of lightly pounding. I tried it and it worked well if you are going to sinew right away.  Some people lay down bundles of sinew on the back of the bow and others lay single strings.  I use single strings to make sure each string is flat and tight in length. It takes more time but I can control the layers of sinew better and keep it flat.  I don't want to sinew more than I have to because there comes a point when you have enough for the job it needs to do. Ferret is another good person for information on sinewing. We have traded info over the years and have experimented with horn bows, short bows, horn belly bows and heavy draw weights. Now days I sinew short recurves for horse bows and that's about it. Keep up the sinew along, maybe some guys can show pictures of their sinew bows and tell the story.  Great post Keenan.

[snag]

So when you are "sizing" the bow with glue do you let that first glue dry or are you just applying the glue and then you immediately start applying the sinew to the bow?

[Keenan]

I have done it both ways Snag and noticed no real difference. The first coat will soak in real fast so I generally start with a good saturation, let it sit for about 30 minutes, then wet it again before laying on the sinew.

[Osagetree]

Nice shop! And thank you!!

[SEMO_HUNTER]

That was great Keenan, very informative and to think that I've been throwing that part of my deer away all these years!
I had read about sinew, but know absolutely nothing about it except that it's hard to chew and taste like crap!    :p  

I'm adding this one to my favorites, and I may have a couple of kids bows that I just built that will be needing some sinew in a year or so?
How much can you expect the poundage to go up with "X" thickness of bundles on the back of a bow?
Also, can you use sinew to void out a splinter?

Thanks!    

[red hill]

Thanks, Keenan. Very well-explained post.  One question, though. How much sinew for an average bow?
Oh, and can you post some pics of your bowhorse. I've glimpsed it a few times on various posts and it looks more user friendly (comfortable) than the wooden horse I made.
Stan  :p

[snag]

That bowhorse looks like it has a drift boat seat, and parts off the boat trailer...good idea!

[Knawbone]

Iv been woundering just how that was done, now I know, thanks Keenan. Yea what he said, how much poundage does it add.

[SEMO_HUNTER]

I was thinking the same thing Snag, I have a seat just like that in my 2 man bass boat that I use on the river down here. Keenan has got the set up right, I'm always standing up.

[Keenan]

Semo, You can gain between 5-10 pounds depending on the amount of sinew used. It also depends on the wood type and if you heat treat the belly that can raise the poundage as well.
 Yes it will help hold the splinters down. The main reason for sinew is to give the back some protection, and it also helps to induce reflex.
 On this bow I just did one heavy layer of sinew. The amount you see on the bench, is just under half, of what I used. It's hard to say how many tendons because they always very in size and length. These were buffalo leg tendons and fairly long. I think I used 5 or 6 total. I preppared allot so it's hard to remember.
 The bow bench has been an evolving project,That I will share sometime in the future,  

[ChristopherO]

Excellent post, Keenan.
When I built an osage recurve a few winters ago I pretillered it due to lack of experience.  It drew 40# at 28" unbacked.  Then I layered 4 coursed of sinew and left sit for a month under the ceiling fan.  It then only drew 44#'s.  I was very disappointed to say the least.  Upon finishing it up I presented it to my son has used it for 3D shoots since then.  Yet, the last time we put it on the scales it read 57#'s!  It will fluctuate season to season but I don't think it has been anywhere near the 40's once it came unto it's own.  Can't tell you how many times I wished I've kept that bow  

[Keenan]

Christopher, That is very true about sinewed bows. They will fluctuate due to conditions. However that can be minimal depending on amount of sinew and how good it is sealed. That is also one reason I don't generally do allot of sinew. I've found that with one layer of sinew and skin over it with a good sealer, it will stay fairly stable. I have had several creep up in poundage over a little time. One month is sometimes to short to be considered fully cured for 4 layers of sinew. I have had a few bows over the years that I had a hard time parting with. I still have my first all wood bow that I made. However the very first two bows were that I made, were glass bows when I was a teenager. Somewhere in my late teens early 20s I parted with them have often regretted that. Now 30 years later I have no idea if they still exist.   :rolleyes:

[NYArrow]

Amazing stuff. Thanks for the post! I will have to save this one for quick reference in the future.