Most Primitive people used sinew as a string, thread or similar binding agent as it shrinks as it dries making a very snug fit. The one flaw that sinew has is that it is affected by moisture and can loosen when it is wet. But for this one flaw sinew might be the best binding string the primitive archer has to use.
There are some areas in sinew that are very tough to separate the fibers. Picture 1 shows some of these tough areas. Both pieces of sinew shown in Picture 1 are of the lower part of the rear leg of a White-tail Deer. On the top piece you can see a bent section in the middle of the piece that is shown. This is the section of the sinew that bends around the joint near the meta-tarsal gland. The lower piece also has a tough area where the piece splits into a ‘Y’ at the end of the piece.
Once the sinew is harvest from the Deer or other animal source and dried it is ready to be processed. The way we start to process the sinew is to pound it. The best way to pound sinew is between a hard and a soft object or two hard objects and lightly pounded. Sinew is very tough but if you get carried away in the pounding it will get destroyed and separate too much. Once you over pound it all you will get is small short pieces. You want to break it just enough to be able to pull it apart.
(Shredding sinew Picture)
The dried sinew starts as an amber color and immediately changes to a white as it is pounded. The purpose of pounding the sinew is to loosen the fibers so you can pull them apart into fine threads. So once you start pounding the sinew you should check it often until you become accustomed to how much pounding is needed.
I personally like to take my sinew down in the basement of my house and hit it with a ball pen hammer against the concrete floor lightly. The ball pen hammer has no sharp edges to tear any fibers and the floor is perfectly flat again not to tear any fibers. It only takes 30 seconds to pound a piece once you know what you’re doing. Once I finish a few I take them up on the living room carpet with my family and watch television while I shred the sinew in to fine linen type threads.
In Picture 3 a piece of sinew is being pounded to break the fibers using a stream rounded cobble stone and a flat piece of marble.