The sinew series part 2 – Processing dry Sinew

In this next sinew series article, I’ll attempt to show you how to take the dry tendon material which we created in the previous article and process it into usable sinew.

If you’ve arrived here before reading Part 1 of the sinew series which can be found here: https://southmoorbows.com/the-sinew-series-part-1/ then it may be worth going and reading that article first. If, however, you already have a bunch of dry leg tendon material which you are eager to convert into something which you could back a bow with etc then read on!

Step 1 – Organise you tools and your environment.

First, three tool which you will need:

• Hammer (most types will do)
• Wooden stump/round of timber for anvil
• Blunt knife, or strong thumb nails!

If you wanted to go totally old-school, then replace the hammer with a smooth rounded stone about the size of a large baking potato.

A quick note on your working environment. You want to keep your tendons, anvil, hands and your tools dry and clean at all times. This is not a job that you want to do outside in the pouring rain amid mud, dust and general outdoor detritus. Find a spot under shelter or at least pick a dry day and work in a dry, relatively clean space.

Step 2 – Pound your tendons:

The tough, hard, stiff, dry leg tendons which we made in the previous article will now need to be separated out into thin string like sinew threads. Before this is possible the tendons will need to be softened and separated enough so that the tendons can be pulled apart from one another. The simplest way to soften a dried tendon is to pound it. You don’t have to go nuts and batter the thing into oblivion, but they will need at least a looking at with a hammer or stone before you will be able to pull a tendon apart.

In all seriousness though, if you beat the living daylights out of your tendons then you will damage the stringy structure of the inner sinew. You will know if you have been too heavy handed with the pounding process as over beaten sinew will fall apart into short bits of woolly chaff as opposed to nice long strong stringy threads which are about the same length as the tendon was before you started pounding it.

I find that using a wooden anvil helps to protect the sinew from excessive damage. I only revert to pounding onto a metal or stone/concrete anvil when I’m trying to break up the ends of tendons which have the notoriously stubborn forks in them (read below for details).

On a similar note, if using a hammer as your pounding tool of choice, do make sure you strike the tendon square on. Don’t strike the tendon with the edge of the hammer as this will likely chop at the tendon damaging the inner sinew. What is actually desired is to simply soften the tendon up so that you’re then able to separate out the fibres which are currently entwined together.

Regarding using stones as your pounding weapon of choice, the same rules apply. Sharp edges on your hammer stone will destroy your sinew. Keep your hammer stone smooth and rounded. And if you do choose to use stone/concrete as your anvil, make sure this is also smooth.

Since we have already removed the outer sheaths from the larger thicker tendons, we have significantly reduced the work involved in breaking these tendons apart into usable sinew. If you have dried your tendons with the sheath left on, then you are in for a fair bit of extra work. Tendons dried with the sheath on will need a fair bit more pounding. The tendons used in this demonstration have been separated out from the tendon sheath before drying so minimal pounding will be required.

Take one tendon at a time and hold it by the end. Start by gently pounding away at the middle of the tendon.

The middle section will generally be a little more rounded than the ends which is why I start the pounding in the middle. As I gently pound the middle of the tendon, I will roll the tendon in my fingers so that each hammer stroke makes impact with a slightly different face on the tendon, but in approximately the same section. This will start to break the fibres apart in this area. You may also notice the outer membrane begin to detach from the inner sinew.

Now, whilst continuing to rotate the tendon between your fingers, start to pound away from the middle up towards the end which you are not holding. What this will help to do is avoid creating a flat spot on the tendon.

Flat spots are often how the ends present themselves. These flat areas are difficult to strike at from the side. This makes it harder to break up the ends unless you work up to the ends from the middle. When you work up to the ends from the middle you will transfer the roundness of the middle up into the ends helping to break them up better.

If the tendon you chose that you are pounding has a large fork in one end, then this fork will require a bit more work than the rest of the tendon. The fibres in the fork are interlocked which makes the separation process a bit more challenging. The fork is usually hard to strike at from the side too which adds to the difficulty of loosening this area up.

Just do the best that you can for now and if need be, you can always come back to the hammer again later if the fork fails to break apart once the pulling apart process starts.

Step 3 – Remove outer membrane.

Once you can see and feel that the tendon is softened and beginning to separate you can begin the pulling apart process.

If the tendon is one of the larger types, then there will be an obvious membranous material hanging half on half off at this point. Pull this away from the sinew. Don’t throw this membrane away as this is tendon fascia, and it contains quite a high amount of collogen. It can therefore be added to your pile of sinew scraps which don’t make the grade. All of these sinew scraps and tendon fascia make excellent glue. Save it all!

Step 4 – Begin to pull the tendon apart.

I generally start the pulling apart process at either the end without the fork, or in the middle. Whichever is the loosest. Try first to divide the tendon in to two halves. I usually do this by inserting my thumb nails into the middle and working the sinew apart with my fingertips in order to form a hole roughly in the centre of the tendon. If your thumb nail isn’t doing the job for you then you could try starting the hole with a blunt knife tip of even a small, slotted screwdriver.

Once you have formed a hole then you can push your fingers through it and rip the sinew in two, straight down the middle of the tendon. If the tendon is too well bound together to allow you to do this, then start at the none forked end of the tendon and begin to pull this end apart into 4 – 8 pieces. Rip these individual pieces apart from one another. If they detach from the rest of the tendon completely then excellent. Put these detached pieces to one side ready for further processing later.

If your tendon had a fork in the other end, then the likelihood is that your efforts to separate out the pieces comes to an abrupt end once the piece comes up against the fork.

When I find that all the pieces of tendon remain tightly bound together at the fork, I usually end up returning the whole tendon back to the hammer and anvil. After a bit more pounding of the fork itself, (not where the pieces meet the fork but the fork itself) I will try and tug at each of the separate pieces individually to see if one of them is starting to release.

Once one piece starts to come free then the other pieces will soon follow. Further gentle pounding of the unseparated parts of the fork may continue throughout this process.

Step 5 – Break down your tendons into workable pieces.

Once the fork starts to break apart then it is usually no more of a problem. Simple keep pulling on each of the already separated pieces until one of the pieces pulls completely free from the fork. At this point the fork is usually ready to come completely apart.

Now the fork has lost its grip on the other pieces, begin to pull each individual piece apart from the others. A thick tendon should break apart into about a dozen straw thick pieces.

At this point most, if not all, of the membrane will have detached from the sinew leaving you with a pile of coarsely separated sinew fibres and a small but not insubstantial amount of fascia and chaff.

Take all of your sinew pieces and put them to one side as you move onto the next tendon. Keep running through the same process as before until all of your tendons have been pounded and pulled out into strips of coarsely separated sinew.

To give you an idea of how many tendons you will need to back a bow then let me give you a very rough guide. A long bow, say 66″, I would expect to use at least 3oz of fully processed finely stripped out leg tendon sinew. Maybe aim for 4 oz if you are planning 3 layers.

On a long bow, 2 layers of sinew should suffice as a long bow doesn’t need much assistance in the tension plane. This is because the long length of the bow spreads the tension load well enough without the need for additional support. To be honest, I only ever sinew/rawhide back long bows if it’s a real character bow with a ton of potential weak spots like knots etc.

On a short bow like a plains style bow, there is much more stress on the bow due to the short working section of the limbs. So, on a short bow I’d suggest aiming for 3 layers of sinew.

Even though a short bow has less surface area to back when compared to a long bow, since you are adding an extra layer to a short bow, you will probably still want at least 3oz of dry sinew.

So, the general rule is aim for at least 3oz of fully processed sinew. That normally works out to be about the amount of sinew that you will remove from 8-10 red deer feet.

Step 6 – Reducing your sinew down to final thickness.

Once you have pulled apart all of your tendons you should have a fair pile of very coarsely separated sinew. Keep it dry and clean until you’re in a position to start the finer processing.

I usually save my fine sinew processing for a rainy day at home in front of the fire (AKA YouTube!). Put the kettle on and get yourself comfortable.

Grab a piece of sinew and find the middle of it. As you did before, insert your thumb nail or a blunt knife tip through the middle of the piece. Now tease it apart so that you have two roughly equal pieces. By now these two pieces will probably be about the thickness of baler twine.

Now take one of the two halves and do the same again. Find the middle, part it into two halves and separate them out into two pieces.

Take one of these pieces and do the same again.

Keep going like this until your sinew pieces get down to about the thickness of spaghetti. They will not all be especially round however so don’t be concerned if your sinew looks more like waxed nylon thread. Actually, it is worth mentioning here that white waxed nylon string/thread is a great fake sinew! B50 bow string material is also a good gauge of thickness to go for when splitting sinew.

Step 7 – Straighten your sinew for easy storage and use.

Most of your final sinew pieces will have curled up a fair bit due to the pulling apart process. This makes them awkward to lay flat and pile up neatly. A simple solution to this is to pinch each final piece between your finger and thumb and scrap your thumb nail down the flat side of the sinew piece. Then spin it over and do the same on the other side. This will straighten each piece out nicely so that they will now lay together much flatter. This little tip will help you to arrange all of your finished sinew into nice tidy piles. This helps a lot latter when you come to apply your sinew.

So, there you have it! By now you should be able to take your dry deer leg tendons and process them down into a nice big pile of usable sinew.

In the next Sinew Series article, I will show you how to take all of the sinew/fascia scraps which you will now have, (or the tendon sheaths saved from the first article) and make a glue which you can use to stick your processed sinew to your next primitive archery project.

Until next time!

The Sinew Series Part 1

The very word sinew caries connotations of antiquity. A material of a long-forgotten time. This amazing material has so much use to anyone practicing primitive crafts.

Sinew is extremely strong in tension. It is also flexible in any state and quite elastic when wet, tightening as it dries. Even when sinew is in its completely cured dry state it still possesses an element of elasticity which is one of the reasons that sinew is so effective as a bow backing material.

In addition to backing bows, sinew can also be used for wrapping arrow fletchings, nocks etc, it can be used for making cabling, and unlike many plant fibres strings, sinew is also plenty strong enough to make a great natural bow string. And to top it all off, as wet sinew dries it adheres to itself and whatever it is wrapped around making it the original duct tape!

As well as providing all of these functional benefits, sinew can also be used simply as a decorative material in the same way that rawhide was often used in a lattice of bow limbs throughout the ages.

Sinew is one of those fundamental materials that any budding primitive archer should have knowledge and experience of. But the reality is that supply is very often limited making sinew one of those rarer materials which few have ready access to. (A bit like Osage here in the UK!)

Sinew it is also one of those materials which many are put off using because of fears of complexity, long cure times, or as far as the raw state is concerned, many wish to avoid a messy and time-consuming acquisition!

But the truth is that sinew is easy to source, easy to process and easy to apply once you have a bit of experience.

Our hominid ancestors probably enjoyed this incredibly useful material since we came down from the trees. Indeed, it has likely shaped our evolution. We may not have got as far as we have if it had not been for the discovery of this materials many uses. Just imagine the evolutionary jump that our species would have experienced upon the discovery of a material which has all the properties of self-adhesive baler twine!

There is no doubt that the progression of primitive technologies was aided by the diverse utility of sinew.

This article will be the first of several articles aimed at dispelling many of the myths and fears that surround the use of sinew.

It is my hope that this series of articles will enable anyone to source it, extract it, dry it, process it, apply it, cure it and finally enjoy the functional and aesthetic attributes of one of nature’s special gifts. So, lets break down the basics so that by the end of this series of articles you’ll be able to start incorporating this incredible material into your next primitive archery project.

This first Article will cover; what sinew is, where you can source it, how to remove raw sinew from its source and how to dry sinew.

So first, what is this sinew stuff and where does it come from?

Strictly for the benefit of those who are completely new to primitive archery, sinew is basically dried tendon tissue from a dead animal. It’s that simple. Are all tendons created equally? No. Well at least not in my experience.

Nowadays I almost exclusively use deer leg tendons for bow backing and cordage (including bow strings), and I use deer back strap sinew for lashings/wrappings etc. I’ve tried using tendons from other species such as farmed ostrich, domestic cow, farmed boar and truly wild boar and have concluded that large wild deer sinew is superior to sinew from all of these other animals. Ostrich leg sinew comes a close second however and is lovely and long but the sinews I’ve tried from farmed stock aren’t nearly as strong or elastic as those from a truly wild deer.

Pig/boar feet are not long enough to produce usable tendons which only leaves the back sinew as an option. Personally, I find both domesticated pig and wild/feral boar back sinew to be rather greasy. Wild deer back sinew however rarely has this problem. In fact, I just use deer sinew for everything which requires sinew these days. It needs mentioning though that some deer are just a bit too small to produce the kind of fibre lengths which are useful to us primitive archery folk.

Here in the UK, I’d suggest using nothing other than Red deer, Fallow Deer or Sika stag sinew. The smaller deer such as sika hinds, plus all roe and muntjac are just a bit too small to be worth messing about with however if that’s all you can get, then by all means give them a try. Fibres from smaller wild deer will still have all the other great qualities we’ve already talked about. They’ll just produce shorter fibres.

In the USA Mule/whitetail deer and of course Elk/Moose would all produce excellent tendons of suitable length which will produce lovely long strong sinew fibres. Basically, any wild ungulate with a live body weight over say 50kg/110lb will produce excellent sinew for the purposes of primitive archery.

So where can I get sinew from?

Dry sinew

Dry Sinew can at times be difficult to find. Outside of Ebay there are a few craft shops here in the UK which sometimes stock odd amounts however most of these shops are out of stock for 9/10ths of the year. Ebay is your best bet and there are usually several sellers who can provide you with enough sinew for at least a single sinew backing project. Just search for “deer sinew” on Ebay to see if there is anyone selling sinew in your part of the world.

I myself typically have quite a good year-round stock of dried Red Deer leg sinew available for people to purchase here in the UK all year round. I sell dried sinew on a weight basis. If you would like to buy some sinew directly from me then please use the contacts page to get in touch.

Raw sinew

Raw trimmed sinew is as rare as hen’s teeth as no one in their right mind would go through the process of stripping out leg tendons or trimming and cleaning off back strap tendon unless they were intending on drying them immediately.

Like most bits of dead things, sinew spoils quickly unless it is dried as soon as possible. So, the only place you’re likely to find raw unprocessed sinew is on the animal, or parts of the animal, which grew it in the first place!

All of my sinew comes from Red Deer which have been culled in my local area. Fortunately, I am a deer stalker (and also know lots of other deer stalkers) so I’m very lucky to have access to lots of deer legs. By legs I mean the bottom section of the leg below the ankle joint. Deer foot is probably a better description of the body part of use to us. This is the bit that your average deer stalker/hunter will throw in the bin as there is nothing worth eating on the foot of a deer!

Back Strap Sinew

Back strap sinew only ever comes my way if I’ve shot a deer myself for my own consumption, as the back strap sinew lies directly on top of the back straps (AKA the sirloins). Since no one ever gives up the sirloins of a venison carcass you’ll be doing well to acquire the back sinew unless you shoot/hunt deer yourself.

Even if someone is generous enough to offer you a whole back strap then the silvery sinew sheet which lies across the length of the back straps upper surface will likely have been cut off during the filleting and trimming process.

So, my advice is to find some local deer stalkers/hunters and offer to take their unwanted deer feet away for them. You may have to buy them a beer (or more likely a coffee these days!) but as long as you’re willing to do the processing yourself then this will be the cheapest way to acquire the highest quality sinew material. And possibly for free! In the UK you may be able to locate a deer stalker near you through the forum: The Stalking Directory

Removing tendons.

For now, I shall focus on removing tendons from deer feet. I will do an article on removing, drying and processing back strap sinew in the future.

Here I will show a sequence of photos demonstrating the safe and efficient removal of all of the usable tendons which you will find on the foot of a deer. First things first, here’s a quick list of the tools and equipment you will need to get started:

• Easy clean work surface
• Sharp knife
• Knife sharpener
• Disposable gloves
• Kevlar/chainmail gloves
• Dehydrator (only really necessary in the colder more humid months)
• Cup of tea/coffee (optional!)

Step 1- Remove Skin.

The first step is to remove the skin from the cut end all the way down to the dew claws. This will require cutting away the skin from the bone/tendons/fascia which you will be holding in your free hand.

I’d strongly recommend wearing either a Kevlar or chainmail glove as you will be cutting towards your hand and wrist at times. I prefer to use Kevlar gloves which extend beyond my wrists for extra protection. I wear kevlar gloves on both hands as they also help a great deal in gripping the otherwise slippery skin and bone when it comes to the pulling phase of the skinning process.

In the interest of hygiene, under my Kevlar gloves I wear a pair of disposable gloves.

With the back side of the foot facing up towards you, start the skinning process by pinching the skin away from the large tendon running down the back side of the foot. Begin to slice away a strip of skin that sits directly on top of the tendon. (See pic below)

Next peel away the skin from around the top and front of the foot to expose the whole top of the bone. Be careful here not to cut the front tendon away onto the skin which runs down the front/shin of the leg bone.

Once you have cut a large enough flap of skin free to take a firm grip of the skin, hold the bone in one hand and the skin in your other hand and pull down hard on the skin to free it from the rest of the bone. (See pics below)

Step 2 – Remove tendons.

Once the skin has been pulled down to the same level as the dew claws at the back of the foot, find the thin tendon which runs all the way down the front of the bone. Find a spot about 3” up from the bottom of the skinned section of bone and pinch up this tendon away from the bone. Now insert the end of your knife under the tendon between the tendon and the bone. (See pic below)

Now whilst pulling the tendon upwards and away from the bone, draw the knife under the tendon all the way to the end severing it away from the bone where it terminates. (See pics below)

Now do the same thing to the bottom end of the tendon cutting down about an inch past where the tendon forks across towards the toes. (See pics below)

Some might say that cutting the tendon off at the first fork instead of trimming it out all the way down to the toes wastes a couple of inches of usable sinew. To some extent they would be right. That said though, the sinew beyond the initial fork is intertwined within itself making it difficult to separate out after drying.

Personally, I’m more than happy to make do with the 7-9inches of untangled sinew which is obtainable from tendons removed as per the picture above. I usually revert to using back strap sinew when I need fibres to be longer than 9 inches.

Now flip the deer foot over and repeat the same process to remove the larger thicker tendon located on the back of the foot. (See pics below.)

Step 3 – Remove tendon sheaths.

At this point you will now have two whole tendons, one of which will be skinny and floppy, the other one will be thicker and stiffer. The thin floppy one needs no further attention and can be put to one side ready for drying.

The thicker, stiffer tendon now needs to be separated out into individual tendons after first separating them from the tendon sheath. The removal of the tendon sheath surrounding the inner tendons speeds up drying and also makes the pounding and separating process much easier at a later stage.

To remove the tendon sheath first insert the tip of your knife into the thinner end of the tendon sheath and slip the blade tip between the outer layer of the sheath and the largest of the visible tendons within the sheath. Now cut up towards the thicker end of the tendon. You’re basically trying to cut the sheath open end to end without cutting the tendon on the inside.

Step 4 – Separate the tendons.

Now take your fingers and separate out the tendons from the sheath. On front feet there is one round thick tendon plus two thin tendons. On back feet there will be one thick round tendon plus one thin tendon. Grip the individual tendons one at a time and rip them away from the tendon sheath.

The Kevlar gloves help a lot to provide enough grip to get them all separated out easily. (See pics below.)

Whilst the tendon sheaths do contain some tendon material, processing it away from all the other fascia is a great deal of work so nowadays I save all my tendon sheaths up until I have a bunch of them and then I cook them up into sinew glue.

Sinew glue that I use for backing my bows. I’ll do an article on sinew glue at some point in the future. Until then just remember to keep your tendon sheaths either dried or frozen because they really do make excellent sinew glue!

Step 5 – Dry your tendons.

A quick word about using a dehydrator to dry tendons/sheaths.  Dehydrators are only really necessary when temperatures are low and/or humidity is high.

Most of my deer feet become available to me in the winter months. The winter months in the UK are notoriously wet and cold. Not ideal for drying anything! As such I’ve found a small dehydrator to be extremely useful for drying all my tendons quickly and efficiently.

Being a highly perishable item, tendon needs to be thoroughly dried as quickly as possible. Failure to dry quickly will result in a rotting stinking useless mess. Letting your tendons get even a tiny bit high will result in weakened sinew and a permanent whiff which will win you zero credibility!

If you live somewhere like Arizona however, you’ll likely air dry your tendons adequately by simple hanging then somewhere airy, out of the sun and away from dogs, rats and flies.

Deer tendons are fairly thin so should be dry in good air-drying conditions within a couple of days. A good place to air-dry your tendons in colder climes would be up high above a stove. Make sure you don’t cook your tendons though (see comments below re dehydrating).

If you do choose to air dry your tendons, then avoid letting them get fly blown. Maggots will quickly render your efforts useless.

If using a dehydrator makes more sense to you then heed this warning before embarking on dehydrating your precious tendons! It is very easy to be tempted to crank the thermostat up on the dehydrator to speed the drying process. Whilst this will certainly speed up the drying time it will also cook your tendons rendering them useless for all but glue.

You’ll know when you’ve accidentally cooked a tendon because when you come to pound it and separate out the fibres, your sinew will break apart into short stiff lengths of brittle useless splintery chaff instead of nice long, soft, fluffy, white, stringy lengths of sinew. Too high heat damages the proteins which make up your sinew and maintain the structural integrity of your end product.

You’ll want to dry your tendons using the lowest temp that you can get away with. I set my dehydrator to 130℉/55℃. No higher and no lower. At 130℉/55℃ my tendons are completely dry in 12 hours. No damage, no smell. Just beautiful, dry, stiff, odourless sinew ready to be pounded into wonderful soft fluffy white fibres.

In the next article we will run through the processing of dried tendon into sinew fibres ready for use in your next sinew bow building project. Until then I suppose you’re now wondering what to do with a bucket full of skinned out deer feet.

Until next time!