Sulfur has always been used extensively in pyrotechnics. It serves as a fuel and reduces the ignition temperature of mixtures. It also tends to increase the burning rate and friction or shock sensitivity of most mixtures.
Sulfur can increase the sensitivity of some mixtures, especially those based on chlorate or perchlorate oxidizers. Mixtures of chlorates and sulfur are also known to ignite spontaneously and should therefore be avoided at all times. Mixtures of perchlorates and sulfur are less likely to ignite spontaneously but are still very sensitive and need to be treated with extreme caution. Burning sulfur produces sulfur dioxide gas, inhalation of which should be avoided because it is extremely poisonous.