Cordage from clothing, fabric and plastic bags

A cord does not become strong because one thread is especially tough, but because many fibres work together. With the reverse-wrap method you first twist each strand in one direction and then lay both strands around each other in the opposite direction. Each strand wants to untwist – and in doing so presses itself even more firmly against the other. This opposing tension holds the cord together without any glue or knots.

Braiding with three strands is similar, just without twisting: the strands cross each other in turn and pinch one another in place. A braid is usually a little thicker and flatter than a twisted cord, but it is easy to learn and hardly ever comes undone by itself.

The material plays a part too. T-shirt fabric is a knit (jersey): it stretches, and its cut edges curl in when pulled instead of fraying. Bed sheets are woven; their edges tend to fray, and strips cut from them stay flat. Plastic bags made of thin film stretch a lot under load and slowly give way – a line made from them needs re-tensioning more often.

Even strips matter more than fast work. Every little nick or jag in the cut edge is a place where a tear can start – just as a crisp packet tears most easily at the little notch. So cut with sharp scissors in calm, long strokes and keep the width as even as you can. For a T-shirt, the entry gives about 2–3 cm as the strip width.

When lengthening, stagger the joins: if all strands end and restart at the same point, a weak spot forms there. Twist new strips in with a generous overlap, or join plastic rings with loops. Secure the ends with an overhand knot so nothing untwists.

Also remember that every knot weakens a cord, because it is bent sharply there. That is just as true of bought rope. For a washing line or a bundle it does not matter – but it is one more reason why improvised cord is only fit for light tasks.

Good uses are anything where a break is at most annoying: bundling firewood or a sleeping pad, a washing line in camp or in the garden, a snapped shoelace, a handle for a bag, loops for hanging things on a backpack. At home during a longer power cut, a line made from old textiles can also be handy, for example for drying laundry.

One simple test question helps: "What happens if the cord breaks right now?" If the answer is "then the bundle falls apart", all is well. If it is "then someone falls" or "then something lands on someone", improvised cord is the wrong choice. Climbing, abseiling, securing people, loads above people and towing are explicitly ruled out.

Also, do not sacrifice clothing you need to stay warm. In the cold, a dry jumper is worth far more than a few metres of cord. Use fabric scraps, broken shirts, bags or material that is left over anyway.

The strength of homemade cord is unknown. It depends on the fabric, the strip width, nicks, knots and moisture – and it cannot be reliably estimated without testing equipment. That is why this page deliberately gives no figures, and why the rule has no exceptions: never for people, never for loads above people.

Plastic bags, film strips and long cord loops are dangerous for babies and toddlers because they can suffocate or become strangled. Keep material and finished cord out of reach and do not string lines where small children play or sleep.

When cutting: scissors are safer than a knife. If you use a knife, cut away from your body on a firm surface. Keep cord made from synthetic fabric and plastic away from fire and embers – it melts and can drip.

Practise at home with an old T-shirt, with no time pressure. Cut off the body below the sleeves, then cut one long strip in a spiral and stretch it bit by bit. Then try both methods: once twisting, once braiding. You will soon notice which one comes more easily to you.

Good practice tasks are small and everyday: tying up a bundle of newspapers, stringing a short washing line on the balcony or making a handle for a shopping bag. Watch how much the cord stretches and whether it needs re-tensioning after a day.

With children this makes a nice craft project – as long as adults do the cutting and the finished cords are not used for climbing or swinging. Incidentally, cords braided from fabric scraps were traditionally used for rag rugs too.