Djembé- and dun-dun cord

The very thin white cord below the red black cord already withstands 125 kg before breaking. It can tension a djembé on itself ! The red-black no stretch cord contains three times this quantity of superstrong aramide fiber. To this strength you may add the strength of the low stretch polyester jacket. You may also find cord with a polypropylene jacket but this cord will behave badly as polypropylene stretches very much. The reason is that polypropylene (PP) is much cheaper than polyester.

Cord can be manufactured in many different ways and with many different fabrics and combinations between these. Common fabrics are:

• Nylon (polyamide) (medium stretch)
• Polypropylene (high stretch)
• Polyester (low stretch)
• Dyneema (very low stretch)
• Spectra (very low stretch)
• Aramide (Kevlar, Twaron) All very low stretch
• Vectran (Very low stretch)
• PBO (Zylon) (Very low stretch)

A nylon cord stretches a lot before breaking. UV light will harden the nylon.

Polypropylene stretches even more than nylon. It is cheap but the quality is corresponding because it features also a lot of wear. The cord floats on water. Polyethylene is even worse.

A Polyester cord is more expensive, but resists wear good. It stretches a lot less than nylon or polypropylene.

For low stretch applications the cord can be pre-stretched. For more serious applications a core of dyneema, aramide, spectra, vectran or PBO can be used. By using polyester as the sheath protecting the core against wear and UV light a perfect no-stretch combination is obtained. During production special attention has to be paid to making a very tight sheath.

Dyneema is similar to Spectra. Can be melted easily, floats on water and has extremely low stretch. It was invented by DSM (Dutch State Mines), while Spectra is manufactured by Honeywell.

Aramide (also known under the name Kevlar (Trade mark of Dupont) and Twaron (Teijin company formerly the Dutch AKZO). Aramide shows very low stretch and a high breaking force. Fibres do not melt.

Vectran has the same (yellowish) colour as aramide, but has a still higher breaking force. 

PBO is the most modern fibre in this line-up. Very low stretch, no creep (stretch at long term). Very sensitive for UV light ! Already under a TL light it lost 50% of strength in 24 hours. So the line should never be used without an outer jacket of polyester.