 The main advantage of the latter payloads is their low visibility due to the absence of metals such as sodium and potassium that may be either easily thermally excited and give prominent emissions or give condensed reaction products (such as carbonates and chlorides), which would cause a distinct smoke trail.Pyrophoric flares work on the principle of ejecting a special pyrophoric material out of an airtight cartridge, usually using a gas generator, e.g.a small pyrotechnic charge or pressurized gas.