Ropes and Rope Making, by B.E.

Friday, Jan 11, 2013

Disclaimer: The knowledge below is not comprehensive, but is included to the best of the authors understanding. New research is being published continuously on the subjects below and the author and/or publisher can take no responsibility in the safe or unsafe application of the knowledge included. If you are using ropes for life-support or other dangerous applications please get qualified instruction, and follow all manufacturer’s guidelines! That said...

There are several items, though while not indispensable, can make living through hard times much more comfortable and safe. Ropes can make the hardest of tasks easier and safer when used correctly, from felling trees and towing vehicles to tying up your shoes. Making the most of your ropes and cordage/paracord, practicing safe long-term storage of rope, and even making your own rope are things that anyone can learn and benefit from, and should be a consideration for prepared individuals.
A rope is a tool, and like any other tool it must be taken care of or it will fail when you need it most.

My background comes from using ropes in life-support situations. My life depends on the rope I use on a daily basis, regularly having to hang over 50 feet above the ground. I have a vested interest in keeping it well maintained. The same can be said for anyone who uses a tow strap on a vehicle, a block and tackle pulley system, and any other situation where a failing rope can mean damaged equipment or injured people. I want to offer an overview on the various types of rope, their construction, and safe long term storage. I will also touch on making your own rope with natural materials, either naturally occurring in the wild or even from crops grown specific to the purpose, though these should never be used for life-support applications.
In simplest terms, there are mainly three types of construction: laid ropes, braided ropes and kernmantle ropes, which consist of a braided sheath around a core of inner strands. There are generally three levels of elasticity for ropes: high-stretch ropes, low stretch ropes and static (no-stretch) ropes. Finally, there are two main classes of rope making material: natural fibres and synthetic fibres.

Construction
Laid ropes are the twisted type commonly seen in the cheap yellow nylon camping ropes. They are useful, cheap, and can be made by yourself at home (see below). The trouble with laid ropes is that they can unravel (as you may know if you ever spun around on a tire swing as a kid) and when untwisted they lose much of their strength. For this reason they are no longer commonly used for life-support systems or to hang or lift heavy, free hanging objects. Braided ropes are more often seen in synthetic fibres, and do not unwind, though they are still not generally used for life support systems. They are commonly used in boating and rigging, and can be found in most camping departments in the form of thin white ropes for tying up tarps. They come in all sizes. Lastly, there are kernmantle ropes which is the style most used in life-support systems because of the strength and abrasion resistance of the style of construction. Paracord is a good example of a kernmantle rope, with a braided outer sheath surrounding the core of strands inside. However, paracord is not rated for life support systems! There is endless Internet chatter about whether you can rappel using paracord, and my answer to the question is NO. Although it technically has a breaking strength of about 500 lbs of force, and average 150 lb person can generate upwards of 900 lbs of force when on rappel. Add to that the chance of abrasions and reduced strength due to knotting and the math does not look good.

Elasticity
The elasticity of a rope is a result of its materials and construction. Laid ropes stretch a little by nature of construction, but are not usually rated to a level of elasticity. Braided and kernmantle ropes vary widely, and each level of elasticity has a different use. In general terms, cordage (small diameter, non –life-support rope) is low stretch or static. Only larger diameter kernmantle ropes are able to effectively made as high-stretch ropes. High stretch ropes are used in life-support systems to absorb the shock of falling and weighting the rope (like a bungee cord). These are not very suitable for towing or lifting, because they tend to ‘bounce’ due to their stretchiness. A little give is ok when lifting and towing, a lot is not so good. Most cordage and rope a prepper would purchase for daily household use will likely be low stretch or static in nature.

Materials
Almost all ropes and cordage sold today are synthetic, usually made of nylon or polyester, and sometimes of more specialized patented materials such as Spectra and Dyneema. Natural ropes are less common, as they are generally more susceptible to the elements and less uniform, and are generally made from plants such as hemp, manila and sisal. Each type of material has its own storage concerns, pros, cons, strengths and weaknesses.

Synthetic Materials
Synthetic materials are resistant to moisture, moulds and mildews, unlike natural fibres. They are the materials most commonly used in commercial production of ropes and cords, because they generally outperform natural fibres in most of the categories that matter. The most common synthetic material is nylon, and as such I will focus on nylon the most. Other synthetics are for more specialized uses, such as polyester and polyolefin’s (i.e. Polypropylene).

1. Nylon is a by-product of petroleum refining, and its production was patented in 1938. It created radical new uses and opportunities, ranging from waterproof jackets to the development of working parachutes, to rope making. It is the material used in paracord and most ropes, and is the most versatile of the synthetic materials.

a. Nylon is somewhat susceptible to UV light, and if you are storing it long term it should be kept out of direct sunlight. I have narrowly missed serious injury when, attempting to climb to a tree stand platform, I casually grabbed a cheap yellow nylon camping rope left out in the sun for two years. Thankfully, before putting my full weight on it several body lengths off the ground, I carefully pulled on it, gradually adding my body weight. It slowly stretched like a rotten elastic band and broke with only the pressure of pulling it with one arm. Needless to say, cheap yellow camping rope is not good choice for life-support applications!

b. Nylon is very susceptible to acids and moderately susceptible to alkalis, even the alkalis from curing concrete in basement floors. Nylon ropes should not be stored directly on concrete or near any other acids/alkalis, such as car batteries in the trunk of a car, or near chlorine (i.e. Bleach or pool shock) and other bleaching agents like hydrogen peroxide, or near phenols, xylenols (used in pesticides) and cresol (used pesticides, deodorizers and disinfectants – I.e. Lysol).

c. Nylon is susceptible to heat, even the heat produced from friction. An interesting demonstration can be done using nylon mil-spec webbing (commonly used for creating tie-offs and anchor points to attach to a rappel rope) and a kernmantle rope. Simply tie up the webbing to a beam or hook in a loop, pass the rope through the loop, and move the rope back and forth like a saw, pulling down with your bodyweight. The nylon webbing will be cut by the rope like butter with a warm knife. It is a sobering demonstration. Yet nylon, in general, has higher heat resistance than other synthetic fibres like polyolefin’s. Its melting point is around 480 degrees F, slightly lower than that of polyester.

d. Nylon absorbs water, up to 5% of its weight. It loses up to 15% of its strength when wet, and also shrinks. When it dries it will generally resume its original qualities, all else being equal.

e. Nylon sinks in water, has good strength, and most importantly has excellent shock absorption qualities, which is why it is used so often in climbing ropes and other high-stretch ropes. Because of this, nylon is the clear choice for most ropes out there. But it should be noted that the weave construction of the rope can be as important or more important than the materials used, and there are ropes made of nylon that do not absorb shock very much at all (low-stretch and static ropes). Its abrasion resistance is good compared to other synthetics.

2. Polyester: Polyester is gaining in popularity in low-stretch ropes because of its resistance to UV light degradation and to acids.
a. It absorbs less water than nylon (less than 1% of its weight) and loses less strength when wet (about 2%). It is useful in wet environments, such as boating and yachting, although it does not float.
b. Polyester has about the same heat resistance as nylon, with a melting point of about 500 degrees F. Friction heat still applies, and can slice through polyester easily!
c. Polyester has much poorer shock absorption than nylon, and as such it is mostly used in low-stretch and static ropes.
d. Polyester had excellent resistance to acids, but is very, very susceptible to alkalis. The “keep off concrete” rule is even more important with polyester.
e. It has excellent resistance to UV light.

3. Polyolefins: These are generally specialty ropes, and are used in river and water rescue as throw bags, and industries where acids and alkalis are common. Varieties include polypropylene and polyethylene, among others.
a. Polyolefins have high resistance to acids, and good resistance to alkalis.
b. Polyolefins float, making them very good for life-guarding, river rescue, boating, and any other water application where you do not want a rope to sink.
c. They have average to poor susceptibility to UV light, worse than both nylon and polyester.
d. They have a relatively low melting point (about 300 degrees F), much lower than polyester and nylon.
You may also come across specialty rope materials like Spectra or Dyneema, which have been developed for life-support systems. They are generally used as secondary materials in cordage, rather than in a life-support rope, but have their uses. They have virtually no stretch, absorb little or no water, and generally have very good resistance to UV, acids and alkalis. However, they are expensive and specialized. They are hard to work with - you need wire cutter to cut them! They do not melt and scissors are hopeless on them! Unless you have a specialty need for them, nylon will suffice in most applications, and is by far the more affordable option.

Natural Fibres & Rope Making
Natural fibres are not common in commercial ropes, because they rot and degrade over time, even in ideal storage conditions. They are susceptible to mildew, absorb water and are harder to construct ropes commercially due to their limited length. A molten nylon thread can be extruded to any length; a natural fibre is limited by the size of the plant, and must be twisted to form a thread.
The main benefit of natural fibre ropes is that you can make them yourself, and rather simply at that. Natural fibre ropes are almost exclusively “laid” ropes, sometimes called hawser-laid, which is the twisted-style found commonly in the cheap yellow camping ropes I mentioned earlier. It is one of the oldest methods of making rope, and works quite well, but as mentioned before is prone to unwinding which causes a loss of strength. Laid ropes can be made out of many local materials (from thistle to wolf willow to yucca) by hand. To do so, you twist fibres in your fingers or roll them along the top of your leg until it makes a rough string, adding bits of material as you go along to make the string longer. It doesn’t matter if the string is pretty, that will smooth out later. Then take the string and bend it in half, and start twisting it tighter and tighter until it starts to buckle and bend in the middle. Keep twisting and the two halves will bend around each other to form a two-strand laid cord. If you add another string, you can twist and work it into the cord to make a three strand laid cord, which is the most common style and quite strong for its size. You can make it out of anything. Tree bark, grass, heck – the Mythbusters television show even made one out of toilet paper to demonstrate ways of ‘breaking out of prison’. It even held a person’s body weight for ‘most’ of the descent down a multi-story building. Though I wouldn’t recommend that last one.

Adding a step up in technology, you can increase your ropemaking efficiency by using simple bushcraft and homesteader techniques such as a pendulum spinner or a rope making machine.
I made my first spinner years ago out of a piece of firewood and a stick, by shaping a chunk of wood into a board with a hatchet. I made a hole near one end with a knife and mallet, and whittled the stick down so it would slide almost all the way through the hole, but stop before going through. It looked like a noise-maker from a football game. Using a twine like sisal, or some other natural fibre, it is easy to make a rope long enough for binding and lashing logs together, and they can be made to quite long lengths with some helping hands and ingenuity. I will leave it to the boy scouts to describe it further here. A professor I knew actually tested breaking strength of sisal rope made this way, and found his rope (although you should not use this as a rule of thumb!) had a breaking point of about 900 lbs, with a safe working load of much less, of course. An interesting idea would be to use paracord (which generally has a 500 lb limit) and make a 3 strand laid rope from it, which would have a 1,500 lb limit when untwisted and un-knotted. Its twisted strength would be greater due the friction in the laid construction, but without knowing exactly how great, the minimum known safe working limit should be adhered to. But your mileage may vary, and practice caution when creating franken-ropes.

A rope making machine is more complex, closer to a cottage industry than bushcraft, but they are easy to construct out of plywood from plans online. I found it best explained here, but there are certainly other plans that are equally as good.
One final consideration in making your own rope is finishing the rope ends with a whipping or a knot. If they are left unfinished the rope will unravel with the mildest use. In my experience I have found this to be the best and tidiest looking method of whipping rope ends, but there are others as well.

To Conclude
Whether you store synthetic rope for future use in the form of rolls of nylon paracord, want to make a replacement bowstring from dental floss, or need to make that fire-bow drill string out of shoelaces or tree bark for an emergency fire, knowing the safe storage techniques and practicing the skills can be the difference of having and having-not. Look at your stores, see where they are kept, and organize your storage for the best long term results of your materials. The conditions of storage for nylon and polyester ropes are also applicable to the storage of nylon and polyester tents! So if you have materials they are lying around on bare cement or right next to the bleach, you may want to think twice about your organization of equipment. Take care of your tools!


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