Abstract: An explosive device is provided, containing an explosive formulation or explosive ink, which is capable of being disposed of onto a substrate for the device by well known printing and depositing techniques, such as screen printing, ink jet printing or gravure methods. The formulation contains an ink resin binder, a metal and a non-metal in particulate form where the diameter of the particles is less than 10 ?m, such that when the formulation is heated, a reactive output results. The substrate can be chosen from any inert material or alternatively an energetic material for which the formulation provides a means of initiation. Preferred metals are aluminum iron or titanium and non-metals are carbon, silicon, boron or metal oxides such as copper oxide, nickel oxide or molybedenum oxide. Devices according to the invention may take the form of a; pyrotechnic train, initiators, fuseheads, initiators for gas generators, microthrusters, and may form part of a larger system containing energetic materials.