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A smoke bomb is a firework designed to produce smoke upon ignition. Smoke bombs are useful to airsoft games, paintball games, self-defense and pranks. They are also used in smoke tests.
The smoke bomb was first created in 1848, by UK inventor Robert Yale.[why?] He developed 17th-century Chinese-style fireworks and later modified the formula to produce more smoke for a longer period of time. Early Japanese history saw use of a more rudimentary form of the smoke bomb. Explosives were common in Japan during the Mongol invasions of the 13th century. Soft cased hand-held bombs were later designed to release smoke, poison gas and shrapnel made from iron and pottery.
Colored smoke devices use a formula that consists of an oxidizer (typically potassium nitrate, KNO3), a fuel (generally sugar), a moderator (such as sodium bicarbonate) to keep the reaction from getting too hot, and a powdered organic dye. The burning of this mixture evaporates the dye and forces it out of the device, where it condenses in the atmosphere to form a "smoke" of finely dispersed particles.
Home-made smoke bombs, even preceding Yale's 1848 invention, were and are most commonly used in pranks and street conflicts. They are typically made from materials that burn poorly and contained in vessels with limited air intake that thwart combustion. Because both the ingredients and uses are unpredictable, home-made smoke bombs are often categorized as an incendiary device.