A method of forming a very small, i.e. microliter, finely detailed explosive train for the ignition of energetic munitions—which train is formed by ink jetting picoliter volume droplets of an explosive ink onto the substrate; which explosive ink is a pure liquid that will not clog the ink jet printer. The explosive ink being a solution composed of a secondary organic explosive solute, a polymeric binder solute, and a polar aprotic organic solvent. Where the ink jet printer is a commercial piezoelectric type, drop-on-demand, ink jet printer capable of precisely delivering the subject picoliter volume droplets. And, which printer is capable of heating said substrate to an elevated temperature to more rapidly evaporate the solvent, leaving the desired, finely detailed, efficacious, crystalline explosive train.