Semtex is a general-purpose plastic explosive containing RDX and PETN. It is used in commercial blasting, demolition, 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 groups and rebels or terrorists because prior to 2000 it was extremely difficult to detect, as in the case of Pan Am Flight 103. 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. 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. 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 where the mixture was first manufactured starting in 1964. The plant was later renamed to become Explosia a.s., 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. 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 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