Flash powder is a pyrotechnic composition, a mixture of oxidizer and metallic fuel, which burns quickly and produces a loud noise regardless of confinement. It is widely used in theatrical pyrotechnics and fireworks (namely salutes, e.g., cherry bombs, M-80s, firecrackers, and cap gun shots) and was once used for flashes in photography. Different varieties of flash powder are made from different compositions; most common are potassium perchlorate and aluminium powder. Sometimes, sulfur is included in the mixture to increase the sensitivity. Early formulations used potassium chlorate instead of potassium perchlorate. Flash powder compositions are also used in military pyrotechnics when production of large amount of noise, light, or infrared radiation is required, e.g., missile decoy flares and stun grenades. History Lycopodium powder is a yellow-tan dust-like powder historically used as a flash powder. Today, the principal use of the powder is to create flashes or flames that are large and impressive but relatively easy to manage safely in magic acts and for cinema and theatrical special effects. Mixtures Normally, flash powder mixtures are compounded to achieve a particular purpose. These mixtures range from extremely fast-burning mixtures designed to produce a maximum audio report, to mixtures designed to burn slowly and provide large amounts of illumination, to mixtures that were formerly used in photography. Aluminium and chlorate The combination of aluminium powder and potassium chlorate is unstable, and a poor choice for flash powder that is to be stored for more than a very short period. For that reason, it has been largely replaced by the potassium perchlorate mixtures. Chlorate mixes are still used when cost is the overriding concern because potassium chlorate is less expensive than perchlorate. The simplest is a two-component chlorate mix, although this is rarely used. KClO3 + 2Al → Al2O3 + KCl The composition is approximately 70% KClO3 : 30% Al by weight for the reactants of the above stoichiometrically balanced equation. It is considered critically important to exclude sulfur and any acidic components from these mixtures. Sulfur oxidises and absorbs moisture to produce sulfuric and thionic acids; any acid in the mixture makes it unstable. Sometimes a few percent of bicarbonate or carbonate buffer is added to the mixture to ensure the absence of acidic impurities. Sulfur is deliberately added as a third component to this mixture in order to reduce the activation energy. However this gives the problem with acid production and instability and