Semtex

Semtex is a family of plastic explosive formulations developed in Czechoslovakia by Explosia a.s. in the 1960s. It is a moldable, stable explosive that can be shaped for demolition and military applications, and its name has become synonymous with plastic explosives in public discourse.

Semtex formulations are designed to be highly malleable and insensitive to minor shocks, while remaining capable of detonation with a suitable initiation system. The exact compositions have been proprietary and vary by variant; public discussions commonly mention Semtex H and Semtex C as two well-known formulations, but details on their ingredients are not officially disclosed.

Semtex gained notoriety in the late 20th century due to terrorist use and illicit trafficking. It has been associated with high-profile incidents and was widely distributed on the international black market after some regional export controls were loosened.

In response, many jurisdictions tightened regulations on the manufacture, sale, and transport of Semtex, requiring licensing, traceability, and enhanced detection. Modern security and regulatory regimes emphasize preventing illicit access, while legitimate users such as military and demolition teams rely on controlled suppliers. Semtex remains a case study in the regulation of plastic explosives and the challenges of detection, with ongoing efforts to improve detection methods and traceability across international borders.