Flash Powder (Permanganate)Edit
Flash powder using Potassium permanganate as the oxidiser is perhaps the most widely made illegal flash powder. Flash powder using Potassium permanganate has gained a reputation for it's fierce and unpredictable reputation, and the many accidents caused by it means that it is never used in legal fireworks.
It is a mixture of the salt Potassium permanganate, and a metal fuel, usually, though not exclusively Aluminium. Sometimes, other chemicals are added, sometimes to stabilise the mix, but often to sensitise the already unpredictable explosive.
Potassium permanganate is popular because of it's availability, low cost compared to safer alternatives, and it's power as an oxidiser.
It is a common, but false perception that Permanganate flash does not deserve it's dark reputation. Potassium permanganate reacts exothermically at room temperature with many compounds which are common in both natural and man made environments. An excellent example is the reaction between Potassium permanganate and glycerin, which rapidly progresses to the point of ignition. Unlike Potassium chlorate, where contaminants such as Sulfur or Phosphorous are easily avoided, many of the organic compounds that react with Potassium permanganate can come from paper, or even contact with human skin.
The presence of water is known to greatly increase the likelihood of accidents with permanganate flash, and even moisture from the air has been attributed to cases of "spontaneous" explosions.
The unpredictability of the mix is another factor that adds to the reputation of Potassium permanganate flash powders. Often the flash powder will withstand a level of friction, shock, heat or static that at another time has caused it to go off unexpectedly. It is a common misconception that crude tests demonstrating no risk of ignition from handling show that it is safer than it actually is.