Secondary crystalline high explosives are disclosed which are suitable for filling very small volume loading holes in micro-electric initiators for micro-electro-mechanical mechanisms (MEMS), used as safe and arm (S&A) devices. The explosives are prepared by adding the such a high explosive to an aqueous first volatile mobile phase, adding such a high explosive to a non-aqueous second volatile mobile phase, mixing the first and second volatile mobile phases and then loading the combined phases into the MEMS device and allowing the aqueous and non-aqueous solvents to evaporate depositing the high explosive. Enhanced adhesion between the deposited high explosive and enhanced rheological properties can be obtained by adding a polymeric binder to both mobile phases.