In a pyrotechnic composition, the morphology (size, shape and surface features) of individual particles in the mixture influences both burn rate and the ease of ignition of the composition. Collectively, the larger, more rounded and smoother the particles, the lower the burn rate and the more difficult it is to ignite the composition. However, the purpose of the current investigation was only to catalogue some particle morphologies that may be useful in forensic identification of unconsumed or residual pyrotechnic evidence. In this study, potassium nitrate was chosen because of its common use in pyrotechnics and because of its similarity with other frequently used pyrotechnic oxidizers.

All samples were prepared for scanning electron microscopy using a double-sided adhesive carbon disk applied to an aluminum post. Particles were mounted to the carbon disk and sputter coated with gold.