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Semtex is a general-purpose plastic explosive containing
RDX RDX (abbreviation of "Research Department eXplosive") or hexogen, among other names, is an organic compound with the formula (O2N2CH2)3. It is a white solid without smell or taste, widely used as an explosive. Chemically, it is classified as a n ...
and
PETN Pentaerythritol tetranitrate (PETN), also known as PENT, PENTA, (ПЕНТА, primarily in Russian) TEN, corpent, or penthrite (or, rarely and primarily in German, as nitropenta), is an explosive material. It is the nitrate ester of pentaerythri ...
. It is used in commercial blasting,
demolition Demolition (also known as razing, cartage, and wrecking) is the science and engineering in safely and efficiently tearing down of buildings and other artificial structures. Demolition contrasts with deconstruction, which involves taking a ...
, and in certain military applications. Semtex was developed and manufactured in Czechoslovakia, originally under the name B 1 and then under the "Semtex" designation since 1964, labeled as ''SEMTEX 1A'', since 1967 as ''SEMTEX H'', and since 1987 as ''SEMTEX 10''. Originally developed for Czechoslovak military use and export, Semtex eventually became popular with
paramilitary A paramilitary is an organization whose structure, tactics, training, subculture, and (often) function are similar to those of a professional military, but is not part of a country's official or legitimate armed forces. Paramilitary units carr ...
groups and rebels or terrorists because prior to 2000 it was extremely difficult to detect, as in the case of
Pan Am Flight 103 Pan Am Flight 103 was a regularly scheduled Pan Am transatlantic flight from Frankfurt to Detroit via a stopover in London and another in New York City. The transatlantic leg of the route was operated by ''Clipper Maid of the Seas'', a Boeing ...
.


Composition

The composition of the two most common variants differ according to their use. The 1A (or 10) variant is used for mining, and is based mostly on crystalline
PETN Pentaerythritol tetranitrate (PETN), also known as PENT, PENTA, (ПЕНТА, primarily in Russian) TEN, corpent, or penthrite (or, rarely and primarily in German, as nitropenta), is an explosive material. It is the nitrate ester of pentaerythri ...
. The versions 1AP and 2P are formed as hexagonal booster charges; a special assembly of PETN and wax inside the charge assures high reliability for detonating cord or
detonator A detonator, frequently a blasting cap, is a device used to trigger an explosive device. Detonators can be chemically, mechanically, or electrically initiated, the last two being the most common. The commercial use of explosives uses electri ...
. The H (or SE) variant is intended for explosion hardening.


History

Semtex was invented in the late 1950s by Stanislav Brebera and Radim Fukátko, chemists at VCHZ Synthesia, Czechoslovakia (now Czech Republic). The explosive is named after Semtín, a suburb of
Pardubice Pardubice (; german: Pardubitz) is a city in the Czech Republic. It has about 89,000 inhabitants. It is the capital city of the Pardubice Region and lies on the Elbe River. The historic centre is well preserved and is protected as an Cultural monu ...
where the mixture was first manufactured starting in 1964. The plant was later renamed to become
Explosia a.s. Explosia a.s. is an explosives manufacturer in Semtín, a suburb of Pardubice in the Czech Republic. The company was established in 1920. Its most famous product is the Semtex plastic explosive Plastic explosive is a soft and hand-moldable so ...
, a subsidiary of Synthesia. Semtex was very similar to other plastic explosives, especially C-4, in being highly malleable; but it is usable over a greater temperature range than other plastic explosives, since it stays plastic between −40 and +60 °C. It is also waterproof. There are visual differences between Semtex and other plastic explosives, too: while C-4 is off-white in colour, Semtex is red or brick-orange. The new explosive was widely exported, notably to the government of North Vietnam, which received 14 tons during the Vietnam War. However, the main consumer was Libya; about 700 tons of Semtex were exported to Libya between 1975 and 1981 by
Omnipol Omnipol is a company based in Prague, Czech Republic, specialising in the trading of defence and aerospace equipment. International sales Omnipol acts as the intermediary in government-to-government sales of defence equipment, supplying air and g ...
. It has also been used by Islamic militants in the Middle East and by the Provisional Irish Republican Army (PIRA) and the
Irish National Liberation Army The Irish National Liberation Army (INLA, ga, Arm Saoirse Náisiúnta na hÉireann) is an Irish republican socialist paramilitary group formed on 10 December 1974, during the 30-year period of conflict known as "the Troubles". The group seek ...
in Northern Ireland. Sales declined after Semtex became closely associated with terrorist attacks. Rules governing the explosive's export were progressively tightened over the years, and since 2002 all of Explosia's trading has been controlled by a government ministry. , only approximately 10 tons of Semtex were produced annually, almost all for domestic use. On 21 December 1988, 340 g (12 ounces) of Semtex brought down a Boeing 747 over Lockerbie, Scotland killing all 259 passengers and crew aboard the aircraft and 11 bystanders on the ground. Also in response to international agreements, Semtex has a
detection taggant A taggant is any chemical or physical marker added to materials to allow various forms of testing. Physical taggants can take many different forms but are typically microscopic in size, included at low levels, and simple to detect. They can be u ...
added to produce a distinctive vapor signature to aid detection. First, ethylene glycol dinitrate was used, but was later switched to 2,3-dimethyl-2,3-dinitrobutane (DMDNB) or ''p''-mononitrotoluene (1-methyl-4-
nitrobenzene Nitrobenzene is an organic compound with the chemical formula C6H5 NO2. It is a water-insoluble pale yellow oil with an almond-like odor. It freezes to give greenish-yellow crystals. It is produced on a large scale from benzene as a precursor t ...
), which is used currently. According to the manufacturer, the taggant agent was voluntarily being added by 1991, years before the protocol became compulsory. Batches of Semtex made before 1990, however, are untagged, though it is not known whether there are still major stocks of such old batches of Semtex. According to the manufacturer, even this untagged Semtex can now be detected. The shelf life of Semtex was reduced from ten years before the 1990s to five years now. Explosia states that there is no compulsory tagging allowing reliable post-detonation detection of a certain plastic explosive (such as incorporating a unique metallic code into the mass of the explosive), so Semtex is not tagged in this way. On 25 May 1997, Bohumil Šole, a scientist who claimed to have been involved with inventing Semtex, committed
suicide Suicide is the act of intentionally causing one's own death. Mental disorders (including depression, bipolar disorder, schizophrenia, personality disorders, anxiety disorders), physical disorders (such as chronic fatigue syndrome), and s ...
at a
spa A spa is a location where mineral-rich spring water (and sometimes seawater) is used to give medicinal baths. Spa towns or spa resorts (including hot springs resorts) typically offer various health treatments, which are also known as balneoth ...
in Jeseník by blowing himself up with explosives. Šole, 63, was being treated there for psychological problems. It was unclear what explosives were used. Twenty other people were hurt in the explosion, while six were seriously injured. According to the manufacturer, Explosia, he was not a member of the team that developed the explosive in the 1960s. According to the producer's 2017 catalog, several variants of Semtex are offered: Semtex 1A, Semtex 1H, Semtex 10, Semtex 10-SE, Semtex S 30, Semtex C-4, Semtex PW 4, and Semtex 90.https://explosia.cz/app/uploads/2017/11/Explosives-catalog-2017.pdf


Notes


References

{{Reflist, 30em


External links


Website of the manufacturer
with
brief history
of Semtex
Manufacturer's rebuttal of various alleged misapprehensions, including involvement of Bohumil Sole
Explosives Products introduced in 1966 Czech inventions