Electric igniters consisting of an electric fuse head and a small charge of igniting powder, generally black powder. An electric fuse head consists of two insulated conductors to the ends of which a conducting metal filament is soldered to form an electrically resistant bridge; this filament is embedded in an igniter bead. It is used to ignite a powder charge or to initiate a primary explosive.
Chemical igniters such as those consisting of a cylinder containing a glass ampoule filled with a chemical product (e.g., sulphuric acid) and a charge of potassium chlorate, the two being separated by a metal diaphragm. When the ampoule is broken the acid eats away the metal diaphragm (which serves as a delay element) and reacts with the potassium chlorate, producing intense heat capable of igniting a powder charge or safety fuse.