Flash powder
From Includipedia, the inclusionist encyclopedia
Flash powder is a pyrotechnic composition, a mixture of oxidizer and metallic fuel which burns quickly and if confined will produce a loud report. It is widely used in theatrical pyrotechnics and fireworks (namely salutes, eg. cherry bombs, M-80s, and firecrackers), and was once used for flashes in photography.
Different varieties of flash powder are made from different compositions; most common are potassium perchlorate and aluminum powder. Sometimes, sulfur is included in the mixture to increase the sensitivity. Early formulations used potassium permanganate instead of perchlorate.
Flash powders, specifically chlorate/perchlorate ones, are unique in that they produce no gas products (all solid products), which means that they are not explosives by scientific definition. In that regard, they are similar to thermite mixtures.
Flash powder like mixtures are used in industry and aerospace for generation of large volumes of gas in gas generators, in pyrotechnic fasteners, and in other similar applications. They are also used in military pyrotechnics, when production of large amount of noise, light, or infrared radiation is required; eg. missile decoy flares and stun grenades.
Flash powders - especially involving aluminum and perchlorates - are often highly sensitive to friction, impact, and static electricity. Even as little as 0.1-10 millijoules spark can set off certain mixtures.
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[edit] Safety and Handling
Flash-powder mixtures pose the serious risks of burn, amputation, blindness and death. They should not be handled by the untrained or inexperienced. Flash powder and flash-powder devices pose exceptionally high risks to children who typically cannot understand the danger, who may be less adept with safe handling techniques, and who tend to suffer more-severe injuries than adults.
Certain formulations, notably Aluminum powder and potassium chlorate with sulfur, become less stable over time and may combust with little or no warning.
If ever mixing flash powder, never make more than 5 grams at a time. Even experienced hobbyists should never make more than 50 grams at a given time.
[edit] Production of flash powder
Hobbyist pyrotechnicians usually use a method called diapering, in which the materials are poured separately onto a large piece of paper, which is then folded up at the corners and gently rocked back and forth until the chemicals are thoroughly mixed. Professionally, automated systems are used to achieve the same result.
[edit] Aluminum and Chlorate
Because of the above mentioned instability, Aluminum powder and potassium chlorate is a bad choice for flash powder. For that reason it has been largely replaced by the potassium perchlorate mixture. Aluminum powder and potassium chlorate is preferred only if cost is important, because potassium chlorate is less expensive than potassium perchlorate.
KClO3 + 2Al → Al2O3 + KCl
[edit] Aluminum and Perchlorate
Aluminum powder and potassium perchlorate make up the only 2 components of a popular and simple type of flash powder. This compound is stable for a flash powder.
The balanced equation for the reaction is:
- 2 KClO4 + 4 Al → 2 Al2O3+ 2 KCl + O2
Generally, 70% potassium and 30% aluminum (or 70g KClO4 plus 30g Al to give you 100g flash powder) mix of potassium perchlorate and aluminum powder works very well. The more finely powdered the materials, the faster the reaction, and the "sharper" the flash. Care must be taken, however, to prevent any sparks or friction while mixing these two chemicals, as those may cause unwanted ignition.
[edit] Magnesium and Potassium Nitrate
Another method for the production of flashpowder is to use a 3:2 ratio of potassium nitrate to magnesium.
- 3 parts Potassium Nitrate : 2 parts Magnesium
The finer ground (mesh) the magnesium is, the faster it will burn and the more smoke it will produce.
[edit] Manganese, Barium Chromate, and Lead Chromate
A mixture of manganese, barium chromate, and lead chromate is used as a time delay mix for pyrotechnic sequencing. It burns without production of gas.
[edit] External links
- Flash Powder Information and Instructions
- The Explosives and Weapons Forum contains a number of flash powder "recipes" using a wide variety of materials.
