Semtex: how a Czech plastic explosive got its name and a convention

Few Czech inventions are as famous abroad, and as seldom mentioned at home, as Semtex. It's a plastic explosive, soft and mouldable, developed in Czechoslovakia and notorious by the end of the twentieth century.

This is a sensitive subject, so the article sticks to history and regulation and gives no technical detail about making or using explosives.

Where the name comes from

Semtex was developed at the chemical works in Semtín, now part of Pardubice in east Bohemia. The name joins the village with the word "explosive". The chemist Stanislav Brebera is usually credited as the inventor, and development took place in the 1960s. The plant is operated today by Explosia, a Czech company. The product was meant for civil and military use, including mining and demolition.

Exports and notoriety

In the Cold War, communist Czechoslovakia exported Semtex widely. In the following decades it was linked to several terrorist attacks, among them the 1988 bombing of Pan Am Flight 103 over Lockerbie. It was manufactured and sold legally by the state, and its reputation outlasted the system that made it.

The marking convention

One reason such explosives were attractive to terrorists was that unmarked plastic explosive was hard for detectors to find. The response was the 1991 Convention on the Marking of Plastic Explosives for the Purpose of Detection, drawn up under the International Civil Aviation Organization. It requires manufacturers to add a detection marker, and Czech producers marked their product. It's a rare example of a quick international agreement driven by a security crisis.

Regulation today

Explosives in Czechia are strictly regulated. Production, storage and sale need licences and records, and exports fall under national and EU controls. Nothing in this is something a visitor to Prague will meet.

What you can see

There's no Semtex museum in Prague, and no reason to look for one. For industrial history, try a Plzeň day trip, the city that built its identity on industry and beer. For the political world that produced the export, our communist Czechoslovakia explainer is the place to start, and Czech literature for newcomers has books that tackle the period.

Pardubice, the home town

Czechs know Pardubice for other things: gingerbread, a long horse-racing tradition and the Velká pardubická steeplechase, held each autumn. It is an easy train trip from Prague. Another Czech export with a better reputation is the beer; see Czech beer consumption.

Reading about it responsibly

A search for the word turns up sensational or inaccurate stories. For authoritative detail on the marking convention, the ICAO publishes the text, and the manufacturer publishes corporate information. Czechia is a member of NATO and the EU, and its defence and chemical industries work under EU and national rules, with export licences required for military and dual-use goods.

Frequently asked questions

Who invented Semtex?

The chemist Stanislav Brebera is usually credited, working at the chemical works in Semtín near Pardubice in the 1960s.

Why is it called Semtex?

The name combines Semtín, the village where it was developed, with the word for explosive.

Is Semtex still made?

Yes, in Czechia by a licensed company, under strict regulation and with detection markers.

Why do plastic explosives have detection markers?

A 1991 international convention requires them, after attacks showed that unmarked plastic explosives were hard to detect.