Primacord is high-powered explosive in the form of a thin, flexible rope.

"Primacord" is actually a brand name, the more general name for this device is detonating cord. Detonating cord is typically used to detonate large explosive payloads from afar in situations when traditional electrical detonators are not called for. It is typically made of pentaerythritoltetranitrate (PETN)*, a less stable chemical relative of TNT. A high-density core of PETN is wrapped in low-friction sythetic or natural fibers, providing flexibility, tensile strength and water-tightness as desired. As with any other high-power explosive, you must hold federal and state pyrotechnic licenses in order to buy, sell or use detonating cord.

Detonating cord usually burns at around 6000-7000 meters per second**. The exact detonation velocity varies by manufacturer, but it is usually such a reliable property that detonating cord is very often used to precisely time the detonation of a sequence of explosive payloads. Because it is easy to cut and manipulate, it is also often used in stage pyrotechnics.

Primacord is a registered trade mark of The Ensign-Bickford company

*When mixed with a great volume of lactose, PETN is also used to prevent cardiac angina.

**Yes, you read that correctly: it burns at over twenty times the speed of sound. Boom.