Potassium Perchlorate (KCIO,,)
This material has gradually replaced potassium chlorate (KC10 3 ) as the principal oxidizer in civilian pyrotechnics. Its safety record is far superior to that of potassium chlorate, although caution - including static protection - must still be used. Perchlorate mixtures, especially with a metal fuel such as aluminum, can have explosive properties, especially when present in bulk quantities and when confined.
Potassium perchlorate is a white, non-hygroscopic crystalline material with a melting point of 6101C, considerably higher than the 356°C melting point of KC10 3 . It undergoes decomposition at high temperature
forming potassium chloride and oxygen gas. This reaction has a slightly exothermic value of -0.68 kcal/mole and produces substantial oxygen. The active oxygen content of KC1O,, - 46.2% - is one of the highest available to the pyrotechnician. Because of its higher melting point and less-exothermic decomposition, potassium perchlorate produces mixtures that are less sensitive to heat, friction, and impact than those made with KC1O 3. Potassium perchlorate can be used to produce colored flames (such as red when combined with strontium nitrate), noise (with aluminum, in "flash and sound" mixtures), and light (in photoflash mixtures with magnesium).