Semtex H
Definition
A plastic explosive manufactured by Explosia a.s. (Czech Republic) containing approximately 41% PETN and 41% RDX in a styrene-butadiene rubber binder. Identified by co-detection of RDX and PETN in post-blast residue at characteristic mass ratios.
- Manufacturer
- Explosia a.s., Czech Republic
- Composition
- Approx. 41% PETN, 41% RDX
- Binder
- Styrene-butadiene rubber
- Type
- Plastic (mouldable) explosive
- Detection signature
- Co-detection of RDX and PETN in similar mass ratio
Common questions
Why is Semtex often linked to terrorism cases in the media?+
Its plastic, odourless, mouldable form made it attractive for concealment before taggant regulations, and it was exported in large quantities during the Cold War era, some of which reached groups later implicated in bombings, which is why the name carries strong forensic and public recognition.
How does an examiner distinguish Semtex residue from other RDX or PETN-based explosives?+
Because Semtex contains both RDX and PETN in roughly comparable proportions, finding both compounds together at a similar mass ratio in post-blast debris is distinctive, whereas products like C-4 contain RDX alone and detonating cord contains PETN alone.
Does modern Semtex contain a detection taggant?+
Following international taggant agreements after 1991, current production formulations can include a volatile marker such as DMNB (2,3-dimethyl-2,3-dinitrobutane) to aid vapor detection, though older, untagged stock manufactured before regulation remains a proliferation concern.
Related terms
- Brisance (Shattering Power)
- The localised shattering effect of a detonation shock wave, measured by the Trauzl lead block test or the sand-crush test. RDX and...
- C-4
- US military standard plastic explosive containing approximately 91% RDX in a di(2-ethylhexyl)sebacate and polyisobutylene binder. White, odourless, malleable. Detonation velocity 8,050 m/s....
- Composition B (Comp B)
- A secondary high explosive formulation of 60% RDX and 40% TNT by mass, melt-cast from the TNT matrix. Used in artillery shells,...
- Detonating Cord (Det Cord)
- A flexible tube containing a PETN explosive core at a standard linear charge density (3.6 g/m for No. 2 cord). Propagates detonation...
- DMDNB
- 2,3-Dimethyl-2,3-dinitrobutane, the primary detection taggant mandated by the 1991 ICAO Convention on the Marking of Plastic Explosives. Required at 0.1% by mass...
- GC-ECD
- Gas chromatography with electron capture detection. Achieves 1-10 picogram detection limits for nitroaromatic (TNT, DNT) and nitramine (RDX, HMX, PETN) explosives. Cannot...
- ICAO Montreal Protocol on Plastic Explosives (1991)
- The Convention on the Marking of Plastic Explosives for the Purpose of Detection, adopted by ICAO following the Lockerbie and UTA bombings....
- LC-MS/MS (Negative ESI)
- Liquid chromatography with tandem mass spectrometry in negative-ion electrospray ionisation mode. Confirmatory method for all conventional secondary explosives and the primary method...
- Oxygen Balance
- A percentage expressing the surplus or deficit of oxygen in an explosive molecule relative to stoichiometric complete oxidation of carbon to CO2...