Smoke bomb

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Home made smoke powder burning

Smoke bombs are a firework designed to produce colored smoke upon ignition. While there are smoke generating devices that are dropped from airplanes, the term "smoke bomb" is typically used to describe the three varieties of smoke devices:

Smoke balls - hollow, cherry-sized spheres of brightly-colored clay filled with a smoke composition. They produce a forceful jet of colored smoke for 10-15 seconds.
Smoke candles - (also called a smoke generator or smoke canister) cylindrical cardboard tubes with a fuse, usually 1½ inch (37 mm) in diameter and several inches long and looking like a giant firecracker. Such devices create a thick cloud of smoke for up to several minutes. Uses include providing smoke for smoke testing and creating a smoke-screen for paintball and airsoft games.
Smoke canister - A metal can that releases smoke when a pin is pulled. Used for signalling by military personnel.

Colored smoke devices use a formula that consists of an oxidizer (typically potassium chlorate, KClO₃), a fuel (generally sugar), a moderant (such as sodium bicarbonate) to stop 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.

A simple smoke powder can be made by gently heating potassium nitrate and sugar in roughly a ratio of 60% KNO3(saltpetre/potassium nitrate) and 40% sugar. The more finely ground the saltpetre and sucrose, the better the smoke bomb. Care should be taken not to let the mixture (which, when ready, will look like sticky lumps) get too hot when heating. This formula has another very similar variant in which the ingredients are left in powder form and the granulated sugar is replaced with Icing sugar.

Difficulty can be encountered in igniting the saltpetre/carmelized sugar mixture, and "cooking" the smoke bomb can also present a hassle. More success could potentially be enjoyed when one adds another flammable substance to the mixture without "cooking" it.

Devices or cartridges containing only the dye are used with an external heat source in a smoke machine.

In the military, smoke bombs are one of the means for creating smoke-screens.