A method of producing an explosive composition comprising a liquid energetic material and sensitizing voids, the sensitizing voids being present in the liquid energetic material with a non-random distribution, which method comprises: providing a flow of liquid energetic material; and delivering sensitizing voids into the flow of liquid energetic material in a series of pulses to provide regions in the liquid energetic material in which sensitizing voids are sufficiently concentrated to render those regions detonable and regions in the liquid energetic material in which the sensitizing voids are not so concentrated.