Thermalite

Thermalite is a specific type of fuse used in pyrotechnic applications. The product was designed to be used in cross matching safety fuses of the Bickford type. As safety fuse is designed to neither give nor take fire through the heavy fuse jacket, ignition may be achieved by punching a hole perpendicular to and through a safety fuse powder core, threading a piece of Thermalite or similar igniter cord through the hole, then gently squeezing the safety fuse with pliers or similar to bring the powder core into contact with the igniter cord. The Thermalite could be ignited by a match, or more certainly by a purpose made igniter, similar to a wire sparkler.