Flash compositions are a class of pyrotechnic effect compositions used in firecrackers as well as in military applications. They are widely recognized as perhaps the most dangerous pyrotechnic compositions. This study investigates binary flash compositions containing aluminum and (per)chlorate oxidizers. The sensitivities of binary flash compositions are measured, their explosive power is compared using micro-scale ballistic mortar testing, and their detonation parameters are calculated using the EXPLO5 code.