This invention relates to apparatus for explosively severing non-metallic material such as aircraft canopy transparencies, egress panels and other structural members. To provide a more effective use of a given amount of explosive, a detonating cord is encapsulated within the material to be severed. This encapsulation protects the cord and maximizes the severance effect of the detonation. The cord may be encapsulated at positions wherein augmented shock waves are used to accomplish fracture along a line away from the detonating cord while leaving the explosion products restricted in the remaining cord cavity.