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Semtex is a general-purpose plastic explosive containing RDX and PETN.[1] It is used in commercial blasting, demolition, and in certain military applications. Semtex became notoriously popular with terrorists because it was, until recently, extremely difficult to detect,[2] as in the case of Pan Am Flight 103.


Semtex was invented in the late 1950s by Stanislav Brebera, a chemist at VCHZ Synthesia. The explosive is named after Semtín, a suburb of Pardubice in the Czech Republic where the mixture was first manufactured starting in 1964.[3] The plant was later renamed to become Explosia a.s., a subsidiary of Synthesia.[4]

Semtex was similar to other plastic explosives, especially C-4, in that it was easily malleable; but it was usable over a greater temperature range than other plastic explosives. There are also visual differences: whereas C-4 is off-white in colour, Semtex is brick-orange.

The new explosive was widely exported, notably to the government of North Vietnam, which received 14 tonnes during the Vietnam War. However, the main consumer was Libya; about 700 tonnes 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 republican paramilitaries such as the Provisional Irish Republican Army (IRA) and Irish National Liberation Army in Northern Ireland.

Exports fell after the name became closely associated with terrorist blasts. Export of Semtex was progressively tightened and since 2002 all of Explosia's sales were controlled by a government ministry.[5] As of 2001[update], approximately only 10 tonnes of Semtex were produced annually, almost all for domestic use.[3]

Also in response to international agreements, Semtex has a detection taggant added to produce a distinctive vapor signature to aid detection. First, ethylene glycole dinitrate was used, later switched to 2,3-dinitro-2,3-dimethylbutane (3,4-dinitrohexane, DMDNB), which is used currently. According to the manufacturer, the taggant agent was voluntarily being added since 1991, years before the protocol signed became compulsory.[3] 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. The shelf life of Semtex was reduced from 10 years guarantee prior to 1990s to 5 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 isn't tagged in this way.[6]

On May 25, 1997, Bohumil Šole, a scientist often said to have been involved with inventing Semtex, strapped the explosive to his body and committed suicide in the Priessnitz spa of Jeseník.[7] Sole, 63, was being treated there for depression. Twenty other people were hurt in the explosion, while six were seriously injured. It should be noted, however, that the manufacturer, Explosia, states that he was not a member of the team that developed the explosive.

[edit] Note

Various sources state that production started in 1964 or 1966. Explosia's brief historical document states it was 1964,[3] but most other credible sources state it was in 1966. Most of these also state that development was started at the same time, in response to a request from Vietnam for a counterpart to the US's introduction of C-4.

Plastic explosive

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C-4 plastic explosive — the off-white rectangular blocks — being used to destroy unexploded artillery components.

"Plastique" redirects here. For other uses, see Plastique (disambiguation).

Plastic explosive (or plastique) is a specialised form of explosive material. It is soft and hand moldable solid material. Plastic explosives are properly known as Putty explosives within the field of explosives engineering.[1]

Common plastic explosives include Semtex and C-4. Plastic explosives are especially suited for explosive demolition as they can be easily formed into the best shapes for cutting structural members, and have a high enough velocity of detonation and density for metal cutting work. They are generally not used for ordinary blasting as they tend to be significantly more expensive than other materials that perform just as well in that field. Also, when an explosive is combined with a plasticizer, its power is generally lower than when it is pure.

[edit] History

The first plastic explosive was gelignite, invented by Alfred Nobel in 1875.

Just prior to World War One, the British explosives chemist Oswald Silberrad obtained British and US patents for a series of plastic explosives called "Nitrols", composed of nitrated aromatics, collodion, and oxidising inorganic salts.[2] The language of the patents indicate that at this time, Silberrad saw no need to explain to "those versed in the art" either what he meant by plasticity nor why it may be advantageous, as he only explains why his plastic explosive is superior to others of that type.

One of the simplest plastic explosives was Nobel’s Explosive No. 808, also known as Nobel 808 (often just called Explosive 808 in the British Armed Forces during the Second World War), developed by the British company Nobel Chemicals Ltd well before World War II. It had the appearance of green plasticine with a distinctive smell of almonds. During World War II it was extensively used by the British Special Operations Executive (SOE) for sabotage missions. It is also the explosive used in HESH anti-tank shells. Captured SOE-supplied Nobel 808 was the explosive used in the failed 20 July plot assassination attempt on Adolf Hitler in 1944.

During and just after World War II a number of new RDX-based explosives were developed, including Compositions C, C2, and eventually C3. Together with RDX these incorporate various plasticisers to decrease sensitivity and make the composition plastic.

The origin of the obsolete term plastique dates back to the Nobel 808 explosive introduced to the US by the British in 1940. The samples of explosive brought to the USA by the Tizard Mission had already been packaged by the SOE ready for dropping to the French Resistance and were therefore labelled in French, as Explosif Plastique. It is still referred to by this name in France, and also by a few Americans. However, most English-speaking users refer to it either by the actual label printed on the packaging (e.g. C-4 or Semtex) or as plastic explosive.

C3 was effective but proved to be too brittle in cold weather. In the 1960s it was replaced by C-4, also using RDX but with polyisobutylene and di(2-ethylhexyl)sebacate as the binder and plasticizer.

Semtex was also developed in the 1960s by Stanislav Brebera by mixing of RDX with PETN and then adding binders and stabilizers.



Explosives - Compositions

In general, high explosives are compositions and mixtures of ingredients capable of instantaneously releasing large amounts of energy and doing work of various kinds on objects and bodies surrounding them. In some cases the useful work that is done is limited only by the energy content of the explosive composition, while in other cases the transfer of energy from the explosive composition to surrounding bodies is controlled to a large degree by the momentum or impulse released by the detonating explosive.


Research and development during World War I yielded amatol (TNT plus ammonium nitrate), an explosive with three times the power of gunpowder. Amatol consists of TNT and ammonium nitrate mixed in either 20 /80 or 50 /50 ratios. When the U.S. entered the war, Amatol was adopted for loading high explosive shells. Owing to shortages of TNT and RDX (cyclonite) most World War II mines had had 50/50 ammonium nitrate and TNT (amatol) warheads. This was a low quality explosive but was later improved by the addition of about 20% aluminum to produce minol.

This explosive is a mechanical mixture of Ammonium Nitrate and TNT. It is crystalline and yellow or brownish, moisture-absorbing, insensitive to friction, but may be detonated by severe impact. It is readily detonated by Mercury Fulminate and other high explosives. Amatol 50/50 has approximately the same rate of detonation and brisance as TNT. Amatol 80/20 (used in Bangalore Torpedoes), produces white smoke on detonation, while Amatol 50/50 produces a smoke, less black than straight TNT. Amatol is used as a substitute for TNT and is to be mainly found in large caliber shells.

Driven by its liquid propellant engine, the V-2 had a range of approximately 200 miles. Its warhead consisted of 2,000 pounds of amatol.


Baratol is a composition of barium nitrate and TNT. TNT is typically 25-33% of the mixture with 1% wax as a binder. The high density of barium nitrate gives baratol a density of at least 2.5.

Early implosion atomic bombs, like the Gadget exploded at Trinity in 1945, the Soviet's Joe 1 in 1949, or India in 1972, used an Composition-B [RDX-TNT mixture] as the fast explosive, with baratol used as the slow explosive.

Composition A

Composition A is a was-coated, granular explosive consisting of RDX and plasticizing was. Composition A is used by the military in land mines and 2.75 and 5 inch rockets. Comp A-3 explosives are made from RDX and wax. Composition A-3 is a wax-coated, granular explosive, consisting of 91% RDX and 9% desensitizing wax. Composition A-3 is not melted or cast. It is pressed into projectiles. It is nonhygroscopic and possesses satisfactory stowage properties. Composition A-3 is appreciably more brisant and powerful than TNT; its velocity of detonation is approximately 27,000 fps. It may be white or buff, depending upon the color of the wax used to coat the powdered RDX. Composition A-3 is used as a fillerinprojectiles that contain a small burster cavity, such as antiaircraft projectiles. It can be used as compressed fillers for medium-caliber projectiles.

Composition B / Comp B

Comp B explosives are made from TNT, RDX, and wax, such as 59.5 percent RDX, 39.5 percent TNT and 1 percent wax. Desensitizing agents are added. Composition B is used by the military in land mines, rockets and projectiles. Cast Composition B has a specific gravity of 1.65 and a detonation velocity of 'about 25,000 fps and is used as a primer and booster for blasting agents.

Composition B is a mixture of 59% RDX, 40% TNT, and 1% wax. The TNT reduces the sensitivity of the RDX to a safe degree and, because of its melting point, allows the material to be cast-loaded. The blast energy of Composition B is slightly higher than that of TNT. Composition B is nonhygroscopic and remains stable in stowage. It has an extremely high-shaped-charge efficiency. The velocity of detonation is approximately 24,000 fps, and its color ranges from yellow to brown. Composition B has been used as a more powerful replacement for TNT in loading some of the rifle grenades and some rocket heads. It can be used where an explosive with more power and brisance is of tactical advantage and there is no objection to a slight increase of sensitivity. While no longer used in newer gun projectiles, some older stocks may be found with Composition B main charges.

                          Factors for Equivalent Weight of 
                          Composition B Explosive Equivalent 
                          Comp B                         1.00
                          PBXN-109                     1.19
                          Tritonal             1.09
                          AFX-777                       1.47
                          AFX-757                       1.39
                          PAX-28                         1.62

Composition B-3

During the development of a series of melt-castable explosive formulations devoid of TNT, non-TNT formulations yielded self-heating temperatures significantly lower than predicted. In other tests, Composition B (59.5% RDX, 39.5% TNT, 1% wax) demonstrated an exceedingly low self-heating temperature that ultimately results in a violent final reaction. It is often processed above its self-heating temperature, yet it is safely processed in 300-gallon melt kettles. Researchers subjected Composition B and its individual energetic components to one-liter cook-off testing. They expanded their investigations to include neat TNT, neat RDX (HRDX), an insensitive RDX (IRDX) essentially absent of microinclusions and voids, and Composition B-3 (60% RDX, 40% TNT) made with IRDX. Following analysis of these tests, researchers also tested an HRDX/TNT (13% HRDX, 87% TNT) mixture.

Neat TNT is thermally destabilized by the presence of RDX, either HRDX or IRDX, indicating that RDX is the trigger in the thermal decomposition process associated with Composition B (HRDX) and Composition B-3 (IRDX). The reaction violence of both neat HRDX and Composition B made with HRDX were exceedingly violent, with either partial detonation or detonation occurring. Additionally, researchers observed that the reaction of Composition B-3 (IRDX/TNT) was more violent than either neat TNT or neat IRDX. Once again, they hypothesized that solubilized RDX in molten TNT was the source of the effect. They believe the high-quality, defect-free crystals of IRDX were modified by a dynamic equilibrium in molten TNT, with IRDX solubilized and reprecipitated as ill-defined, voided crystals similar to HRDX. They suspect these ill-defined RDX crystallites present at cook-off temperatures were the source of the reaction violence at cook-off.

Composition C-3

Compositior C-3 is one of the Composition C series that has now been replaced by C-4, especially for loading shaped charges. However, quantities of Composition C-1 and Composition C-2 may be found in the field. Composition C-1 is 88.3% RDX and 11.7% plasticizing oil. Composition C-3 is 77% RDX, 3% tetryl, 4% TNT, 1% NC, 5% MNT (mononitrotoluol), and 10% DNT (dinitrotoluol). The last two compounds, while they are explosives, are oily liquids and plasticize the mixture. The essential difference between Composition C-3 and Composition C-2 is the substitution of 3% tetryl for 3% RDX, which improves the plastic qualities. The changes were made in an effort to obtain a plastic, puttylike composition to meet the requirements of an ideal explosive for molded and shaped charges that will maintain its plasticity over a wide range of temperatures and not exude oil.

Composition C-3 is about 1.35 times as powerful as TNT. The melting point of Composition C-3 is 68°C, and it is soluble in acetone. The velocity of detonation is approximate y 26,000 fps. Its color is light brown. As with Composition B, Composition C is no longer being used as a gun projectile main charge. However, some stocks may still be in service with Composition C-3 used as a main charge.

Composition C-4 / Comp C-4 Plastic Explosive

The plasticized form of RDX, composition C-4, contains 91% RDX, 2.1% polyisobutylene, 1.6% motor oil, and 5.3% 2-ethylhexyl sebacate.

The Demolition charge M183 is used primarily in breaching obstacles or demolition of large structures where large charges are required (Satchel Charge). The charge assembly M183 consists of 16 block demolition charges M112, four priming assemblies and carrying case M85. Each Priming assembly consists of a five-foot length of detonating cord assembled with two detonating cord clips and capped at each end with a booster. The components of the assembly are issued in the carrying case. The demolition charge M112 is a rectangular block of Composition C-4 approximately 2 inches by 1.5 inches and 11 inches long, weighing 1.25 Lbs. When the charge is detonated, the explosive is converted into compressed gas. The gas exerts pressure in the form of a shock wave, which demolishes the target by cutting, breaching, or cratering.

Using explosives provides the easiest and fastest way to break the frozen ground. However, the use of demolitions will be restricted when under enemy observation. Composition C-4, tetrytol, and TNT are the best explosives for use in northern operations because they retain their effectiveness in cold weather. Dig a hole in the ground in which to place the explosive and tamp the charge with any material available to increase its effectiveness. Either electric or nonelectric circuits may be used to detonate the charge. For a foxhole, 10 pounds of explosive will usually be sufficient. Another formula is to use 2 pounds of explosive for every 30 cm (1') of penetration in frozen ground.

DMDNB (2-3 dimethyl, 2-3 dinitrobutane) is a new, military unique compound used as a tagant in C-4 explosive. Therefore there is no OSHA or ACGIH standard. However, USACHPPM's Toxicology Directorate did a study to determine an Army Exposure Limit. There is no toxicological data for DMDNB's effects on the human body, but tests were done on laboratory animals and they showed a reversible liver hypertrophy in rats that were exposed to DMDNB. An exposure level was determined and a one thousand fold safety factor was used to lower the Army exposure level to 0.15 mg/m^3. (At this level there are no warning properties, i.e. smell, taste, etc.)

Composition H6 / COMP H6

H-6 is an Australian produced explosive composition. Composition H6 is a widely used main charge filling for underwater blast weapons such as mines, depth charges, torpedoes and mine disposal charges. The M21 AT mine is 230 millimeters in diameter and 206 millimeters high. It weighs 7.6 kilograms and has 4.95 kilograms of Composition H6 explosive.

In weapon applications, computational models require experimental data to determine certain specific output parameters of H6 to predict various underwater blast scenarios. To this end, the critical diameter dc, which is the minimum diameter which will sustain a stable detonation, and the limiting value of the velocity of detonation at infinite charge diameter D-infinity, were determined for unconfined cylinders of H6.

Cyclotol [Composition B]

Cyclotol, which is a mixture of RDX and TNT, is an explosive used in shaped charge bombs.


On 30 August 1999 Holston Army Ammunition Plant restarted production of new explosives to fill an order for Composition CXM-3. This is the first new explosive production by Royal Ordnance North America (RONA) as the operating contractor at Holston. CXM-3 will be supplied to Atlantic Research Corporation to fill warheads for the Tomahawk missile system. RONA is also planning to produce other RDX and HMX products, including approximately 800,000 pounds of Composition C-4, by the end of December.


Detasheet is a plastic explosives, manufactured by DuPont containing PETN with nitrocellulose and a binder. It is manufactured in thin flexible sheets with a rubbery texture, and is generally coloured either reddish/orange (commercial) or green (military). In use, it is typically cut to shape for precision engineering charges.


In 1847 a new explosive came into being. This was nitroglycerine, made by treating glycerine with nitric and sulphuric acids. But at first it was even more dangerous to handle than guncotton, for the least shock exploded it, and its violence was terrific. The great chemist Alfred Nobel tried to improve it by mixing it with gunpowder, but the powder did not absorb all the nitroglycerine, and accidents of the most terrible kind became more and more frequent. Yet the new explosive, being liquid, could be poured into crevices in rocks, and was so useful as a blasting agent that its manufacture went on until a large vessel carrying cases of the explosive from Hamburg to Chili blew up at sea. The ship was blown to bits and her crew killed, and the disaster caused so great a sensation that the manufacture of nitroglycerine was prohibited in Sweden, Belgium, and in England. But Nobel still continued his experiments, and at last, after trying sawdust and all other sorts of absorbents in vain, found the perfect absorbent in the shape of keiselguhr-a sort of earth made of fossil shells. The mixture is what we know to-day as dynamite; and in spite of the fact that modern chemistry has produced very many new explosives, some of terrific power, dynamite remains the safest and most widely used of all explosives.

Many attempts have been made to use dynamite in guns; and the Americans at one time built some huge air guns for the purpose of firing large shells, or rather aerial torpedoes, charged with dynamite. But these guns, of which one or two were used in the Spanish-American War, were very cumbersome and slow in use. Nor could they throw a projectile to a greater distance than a mile. So they were soon abandoned in favor of rifled cannon-firing shells loaded with explosives such as cordite or lyddite.

Dynamite was originally a mixture of nitroglycerin and diato-mite, a porous, inert silica. Today, straight nitroglycerin dynamite consists of nitroglycerin, with sodium nitrate, antacid, carbonaceous fuel, and sometimes sulfur in place of the inert filler. It is most commonly manufactured in weight strengths of 20 to 60 percent. Because of the tendency of nitroglycerin to freeze at low working temperature, another explosive oil usually replaces part of the nitroglycerin in a straight dynamite.

Straight dynamite has a high detonation velocity which gives a shattering action. It resists water well in the higher grades but poorly in the lower grades. Straight dynamite generally has poor fume qualities, and is unsuitable for use underground or in poorly ventilated spaces. The use of straight dynamite has declined because of high cost, sensitivity to shock and friction, and high flammability. Ammonia ("extra") dynamites have replaced straight dynamite in most applications.

Ditching dynamite is a name given to 50 percent straight dynamite. Its high sensitivity is advantageous in ditching where sympathetic detonation eliminates the need for caps or detonating fuse with individual charges. Sixty percent straight dynamite is sometimes packaged in special cartridges for uncle rwater work.

Ammonia dynamites (extra dynamite) are the most widely used cartridge explosives. An ammonia dynamite is similar to a straight dpmite except that ammonium nitrate replaces a portion of the nitroglycerin and sodium nitrate. High-density ammonia dynamite is commonly manufactured in weight strengths of 20 to 60 percent. It is generally lower in detonation velocity, less dense, better in fume qualities, and considerably less sensitive to shock and friction than straight dynamite. Extra dynamite can be used effectively where the rock is not extremely hard and water conditions are not severe. It is widely used in quarrying, stripping, and in well-ventilated mines for smaller diameter holes of small blasting operations.

Low-density ammonia dynamite has a weight strength of approximately 65 percent and a cartridge strength from 20 to 50 percent. Like a high-density extra dynamite, it contains a low proportion of nitro-glycerin and a high proportion of ammonium nitrate. The different cartridge strengths are obtained by varying the density and grain size of the ingredients. Several manufacturers produce two series of low-density ammonia dynamite, a high- and a low-velocity series. Both series are of lower velocity and density than high-density extra dynamite. Because of its slow, heaving action, the low-velocity series is well suited to blasting soft material such as clay- shale or where a coarse product such as riprap is desired. It is well suited for use in structural excavation blasting in certain rock types.

Fume qualities and water resistance vary with the cartridge material. Wrappers sprayed with paraffin give fair to poor water resistance and fair fume rating, whereas a paraffin-impregnated wrapper gives very poor water resistance and a better fume rating. The explosive has little more water resistance than that provided by the wrapper. Low-density extra is the lowest cost cartridge explosive available. The composition of low-density ammonia dynamites is similar to that of a 60 percent high-density extra dynamite with a lower proportion of nitroglycerin and a higher proportion of ammonium nitrate.


Blasting gelatin is a rubber-textured explosive made by adding nitrocellulose (guncotton) to nitroglycerin. An antacid is added for stability in storage. Wood meal is usually added to improve sensitivity. Blasting gelatin attains a very high detonation velocity and has excellent water resistance, but it emits large volumes of noxious fumes upon detonation. It is the most powerful of all commercial explosives. Blasting gelatin is also known as "oil well explosive."

Nobel did much more than merely invent dynamite; he also invented blasting gelatine, gelatine dynamite, and gelignite, both of the latter being better suited for rock blasting than pure dynamite. Blasting gelatine was used to pierce the great St. Gothard Railway tunnel through rock so hard that without it the task could never have been accomplished. Blasting gelatine was tried in guns, but burst them, so Nobel set himself to discover an explosive less violent, yet equally clear and smokeless. By mixing nitroglycerine and guncotton he found a comparatively slow-burning powder which he called ballistite, and this, when he gave it to the world in 1888, caused a very great sensation.

Straight gelatin is a dense, plastic explosive consisting of nitroglycerin or other explosive oil gelatinized with. nitrocellulose, an antacid, sodium nitrate, carbonaceous fuel, and sometimes sulfur. Since the gelatin tends to coat the other ingredients, straight gelatin is water-proof. Straight gelatin is the equivalent of straight dynamite in the dynamite category and is manufactured in weight strengths of 20 to 90 percent with corresponding cartridge strengths of 30 to 80 percent. The cartridge strength or the weight strength may be referred to by the manufacturer as the "grade" of the gelatin, a term which is confusing. Straight gelatin has been used in very hard rock or as a bottom charge in a column of explosives. It has been replaced in most applications by a more economical substitute such as ammonia gelatin, brit higher grades are still used in underwater blasting and in deep well shooting.

Straight gelatin has two characteristic detonation velocities, the confined velocity and a much lower velocity which results from insufficient confinement, insufficient initiation, or high hydrostatic, pressure. Extremely high water pressures may cause a misfire. To overcome this disadvantage, high-velocity gelatin has been developed. High-velocity gelatin is very similar to straight gelatin except that it is slightly less dense, more sensitive to detonation, and always detonates near its rated velocity regardless of water pressure or degree of confinement. High-velocity gelatin is particularly useful as a seismic explosive, and is also used in deep well and underwater work.

Ammonia gelatin (special gelatin or gelatin extra) has a portion of the nitroglycerin and sodium nitrate replaced by ammonium nitrate. Ammonia gelatin is comparable to a straight gelatin in the same way that a high-density ammonia dynamite is comparable to a straight dynamite, and was developed as a cheaper substitute. Ammonia gelatin is commonly manufactured in weight strengths of 30 to 80 percent with corresponding cartridge strengths of 35 to 72 percent. Compared with straight gelatin, ammonia gelatin has a somewhat lower detonation velocity, better fume qualities, and less water resistance, although it will fire efficiently even after standing in water for several days. It is suitable for underground work because of its good fume rating. The higher strengths (70 percent or higher) are efficient as primers for blasting agents.

A semigelatin is comparable to an ammonia gelatin as a low-density ammonia dynamite is comparable to a high-density ammonia dynamite. Like low-density extras, semigelatin has a uniform weight strength (60 to 65 percent) with the cartridge strength varying with the density and grain size of the ingredients. Its properties fall betieen those of high- density ammonia dynamite and ammonia gelatin, and it has great versatility. Semigelatin can be used to replace ammonia dynamite when more water resistance is needed. It is cheaper for wet work than ammonia gelatin, although its water resistance is not quite as high as that of ammonia gelatin. Semigelatin has a confined detonation velocity of 10,000 to 12,000 fps, which, b contrast to that of most explosives, is not seriously affected by lack of confinement. Very good fume qualities permit its use underground. The compositions are similar to ammonia gelatin with less nitroglycerin and sodium nitrate and more ammonium nitrate.


H-6 is a binary explosive that is a mixture of RDX, TNT, powered aluminum, and D-2 wax with calcium chloride added. H-6 is an Australian produced explosive composition used by the military for general purpose bombs.

HBX [Hexahydro - 1, 3, 5 Trinitro-8-Triazine]

HBX is a form of high explosive made from TNT, RDX, aluminum, lecithin, and wax. HBX was developed during WWII that replaced the more shock-sensitive TORPEX used in depth bombs and torpedoes. The warhead for the 2.75-inch "Mighty Mouse" rocket was filled with HBX (40 percent RDX, 38 percent TNT, 17 percent aluminum powder, and 5 percent desensitizers) or composition B (59 percent RDX, 40 percent TNT, and 1 percent wax). All Navy warhead filling activities in the TNT Plant ceased in early The major longer range improvements resulting were the Navy's development of HBX type explosives together with asphaltic, "hot melt" liners for bombs and other munitions. The hot melt liners were developed to coat and eliminate metal-to metal pinch points. After the Naval Magazine, Port Chicago, CA accident of 17 July 1944 , HBX and H-6 explosives were developed that incorporated wax and other chemicals to desensitize the explosive and hot melt liners were introduced for lining bombs and warheads to give some thermal protection and eliminate potential pinch points from cracks or fissures in the bomb or warhead case. Later, plastic-bonded explosives were developed for increased thermal protection and fragment impact resistance.



Although ANFO is not generally suitable for military use, since it's troublesome to store without drying out, mixtures of AN and TNT known as "amatols" were used in both WWI and WWII as a means of stretching the supply of explosives. The proportion of AN in the mix ranged from 50% to 80%. A mix of ANFO, TNT, and powdered aluminum enhancer named "Minol" is still in use [40% TNT, 40% ammonium nitrate, 20% aluminum]. Owing to shortages of TNT and RDX (cyclonite) most World War II mines had had 50/50 ammonium nitrate and TNT (amatol) warheads. This was a low quality explosive but was later improved by the addition of about 20% aluminum to produce minol.


The melt-cast explosive Octol is a TNT-based explosive (70% HMX:30% TNT or 75 percent HMX, 25 percent TNT). Explosives to be stored on Navy ships must not contain TNT or Octol.


The ideal high-energy explosive must balance different requirements. HE should be easy to form into parts but resistant to subsequent deformation through temperature, pressure, or mechanical stress. It should be easy to detonate on demand but difficult to explode accidentally. The explosive should also be compatible with all the materials it contacts, and it should retain all its desirable qualities indefinitely.

No such explosive existed in 1944. While using what was available to meet wartime demands, scientists at Los Alamos began to develop a high-energy, relatively safe, dimensionally stable, and compositionally uniform explosive. By 1947, scientists at Los Alamos had created the first plastic-bonded explosive (PBX), an RDX*-polystyrene formulation later designated PBX 9205. Although other PBXs have since been successfully formulated for a wide range of applications, only a handful have displayed the combination of adequate energy content, mechanical properties, sensitivity, and chemical stability required for stockpile nuclear weapons. Since the 1960s, Livermore has been researching and developing safer HE for Livermore-designed weapons.

The plastic coating that binds the explosive granules, typically 5 to 20% of each formulation by weight, is what gives each PBX its distinctive characteristics. Pressing a PBX molding powder converts it into a solid mass, with the polymer binder providing both mechanical rigidity and reduced sensitivity to accidental detonation. The choice of binder affects hardness, safety, and stability. Too brittle a PBX can sustain damage in normal handling and succumb to extreme temperature swings or thermal shocks, while too soft a PBX may be susceptible to creep and may lack dimensional stability or strength.


PBXN-5 is referred to as a plastic-bonded explosive because it is an explosive coated with plastic material. The composition is made of 95% HMX and 5% fluoroelastomers.

The Anti-Personnel Obstacle Breaching System (APOBS) Detonating Cord Assembly consists of PBXN-8 explosive, silicone rubber, polyamide yarn type I and II, and composition A-5 explosive. Grenade Assembly consists of PBXN-5 explosive booster pellet, PBXN-9 explosive pellets, grenade tube, and male and female grenade shells. Grenade Assembly consists of PBXN-5 explosive booster pellet, PBXN-9 explosive pellets, grenade tube, unisex grenade shells, and ring clamp.


China Lake designed, developed, and qualified the Tomahawk Block III WDU-36 warhead in 48 months to meet evolving Tomahawk requirements of insensitive munitions ordnance compliance and range enhancement, while maintaining or enhancing ordnance effectiveness. The WDU-36 uses a new warhead material based upon prior China Lake warhead technology investigations, PBXN-107 explosive, the FMU-148 fuze (developed and qualified for this application), and the BBU-47 fuze booster (developed and qualified using the new PBXN-7 explosive). Block III was first used in the September 1995 Bosnia strike (Deliberate Force) and a year later in the Iraq strike (Desert Strike).


PBXN-9 Explosive is made for the HELLFIRE/Longbow Missile System. Because of its acceptance into a number of fleet uses, additional characterization and performance tests were conducted on PBXN-9 to support various warhead developmental efforts. Included are the results of various explosive performance tests, such as detonation pressure, cylinder expansion (cylex),and wedge tests, as well as additional material sensitivity studies (large-scale gap test and small-scale gap test).

The JASSM contains the WDU-42/B (J-1000), a 1000-pound class, penetrating warhead with 240 pounds of AFX-757. AFX-757 is an extremely insensitive explosive developed by the Air Force Research Laboratory/High Explosives Research and Development Facility, Eglin AFB, Fla. The fuze is the FMU-156/B employing a 150-gram PBXN-9 booster.

The Anti-Personnel Obstacle Breaching System (APOBS) Detonating Cord Assembly consists of PBXN-8 explosive, silicone rubber, polyamide yarn type I and II, and composition A-5 explosive. Grenade Assembly consists of PBXN-5 explosive booster pellet, PBXN-9 explosive pellets, grenade tube, and male and female grenade shells. Grenade Assembly consists of PBXN-5 explosive booster pellet, PBXN-9 explosive pellets, grenade tube, unisex grenade shells, and ring clamp.

A Low-Energy Exploding Foil Initiator (LEEFI) is a low-energy input device with high-energy output that can detonate a main charge of PBXN-9.



This explosive is one of the new plastic-bonded explosives. It is a cast-cured explosive composition made from a homogeneous mixture of RDX in a plasticized polyurethane rubber matrix. Once cured, the material cannot be easily restored to a liquid state. The finished material is flexible and will absorb considerably more mechanical shock than conventional cast or pressed explosives.




PE4 is a conventional plastic explosive, widely used for the production of improved energetic systems for defensive and offensive use. PE4 is RDX based and is available in cartridge and bulk form. An extrudable for DEMEX 400 is also available. Distinctive standard colours indicate the explosive component: C4, or PE4 ( British) is white and Semtex-H is orange.


Pentolite is a mixture of equal parts of TNT and PETN. When cast, it has a specific gratity of 1.65 and a confined detonation velocity of 24,000 to 25,000 fps. Cast pentolite is used as a primer and booster for blasting agents where its high detonation pressure assures efficient initiation of the blasting agent.


Semtex is an explosive containing both RDX and PETN. Semtex, a Czech-made explosive, has been used in many terrorist bombings. Dynamite has been replaced by the more destructive and easily concealed Semtex. SEMTEX is a plastic explosive that is odorless. SEMTEX along with a detonating cap, can be inserted inside a 5" x 6" musical greeting card, undetected. Three pounds of Semtex plastique packs enough punch to raze a two-story building. Terrorists attack with no warning and no rationale. Their weapon of choice is a pliable, odorless substance that is twice as powerful as TNT and is virtually invisible to conventional security devices. It can be hidden in a brief case or a small cassette recorder.

Czechoslovakia was among the world's chief arms exporters. It sold hundreds of tanks, thousands of firearms and large quantities of Semtex to Iran, Iraq, Libya, Syria, Cambodia and other trouble spots, a practice that stopped long ago. In 1985 and 1986, the Irish Republican Army [IRA] took delivery of nearly 120 tons of arms and explosives from Libya, including a ton of Semtex explosive and 12 SAM-7 surface-to-air missiles. Some of those weapons and explosives have been used by the IRA in terrorist attacks in the United Kingdom and in other European countries. Libyan terrorists used Semtex in 1988 to down Pan Am Flight 103 over Lockerbie, Scotland, killing 270 persons.

The on-again, off-again export of the general-purpose plastic explosive Semtex, manufactured in Czechoslovakia during the height of the Cold War and linked to terrorist groups around the world, resumed in 1994. The Czech Republic recently announced that exports were beginning to selected countries. The first Semtex shipment under the resumed exportswent to the British Defense Ministry. Czech reporting suggested that the British authorities intend to run experiments on the explosive that is often used by Irish Republican Army terrorists-including the October 1993 destruction of a building in Belfast.

According to the 1991 international convention signed in Montreal, Semtex intended for industrial applications is to be a bright red-orange color and detectable by security-monitoring equipment. Variants of the explosive produced for civilian purposes are also less powerful than the nearly odorless version that became a favorite weapon of terrorists. Despite this and the export ban that had earlier been in place, Semtex continues to be smuggled across borders.

Substantial quantities of the explosive have been stolen from industrial enterprises in the Czech and Slovak republics for sale on the black market. Shortly before the most recent ban was lifted, Czech police seized 100 kilograms of industrial Semtex from a group of Czech citizens who were planning its illegal sale abroad. In Slovakia in October 1993, some 900 kilograms of the explosive were stolen from the warehouse of a private firm, together with more than 2,000 detonators. Czech officials candidly admit that they have no idea how much Semtex has been stolen or illegally diverted, and the continued black market trade in the explosive seems certain.


Slurries, sometimes called water gels, contain ammonium nitrate partly in aqueous solution. Depending on the remainder of the ingredients, slurries can be classified as either blasting agents or explosives. Slurry blasting agents contain nonexplosive sensitizers or fuels such as carbon, sulfur, or aluminum, and are not cap sensitive; whereas slurry explosives contain cap- sensitive ingredients such as TNT and the mixture itself may be cap sensitive. Slurries are thickened and gelled with a gum, such as guar gum, to give considerable water resistance.

Since most slurries are not cap sensitive, all slurries, even those containing TNT, are often grouped under the term blasting agent. This grouping is incorrect. A blasting agent, as defined by the National Fire Protection Association, shall contain no ingredient that is classified as an explosive.

Slurry blasting agents require adequate priming with a high-velocity explosive to attain proper detonation velocities, and often require boosters of high explosive spaced along the borehole to as sure complete detonation. Slurry explosives may or may not require priming. The detonation velocities of slurries, between i2,000 and 18,000 fps, vary with ingredients used, charge diameter, degree of confinement, and density. The detonation velocity of a slurry, however, is not as dependent on charge diameter as that of a dry blasting agent. The specific gratity varies from I.i to i.6. The consistency of most slurries ranges from fluid near iOOO F to rigid at freezing temperatures, although some slurries maintain their fluidity even at freezing temperatures. Slurries consequently give the same advantageous direct borehole coupling as dry blasting agents as well as a higher detonation velocity and a higher density. Thus, more energy can be loaded into a given volume of borehole. Saving in costs realized by drilling smaller holes or using larger burden and spacing will often more than offset the higher cost per pound of explosive. Adding powdered aluminum as a sensitizer to slurries greatly increases the heat of explosion or the energy release. Aluminized slurries have been used in extremely hard rock with excellent results.

A slurry and a dry blasting agent may be used in the same borehole in "slurry boosting," with the buk of the charge being dry blasting agent. Boosters placed at regular intervals may improve fragmentation. In another application of slurry boosting, the slurry is placed in a position where fragmentation is difficult, such as a hard toe or a zone of hard rock in the burden. The combination will often give better overall economy than straight slurry or dry blasting agent.


Tetrytol is a mixture of ~70% tetryl (2,4,6-trinitrophenyl-methylnitramine) and ~30% TNT (2,4,6-trinitrotoluene. In 1944 the M104 auxiliary booster was first given to Redstone Arsenal as an experimental order with instructions to develop a manufacturing procedure for loading it with tetrytol. The booster had heretofore been loaded with tetryl pellets. The tests that Redstone conducted showed that tetrytol-loaded M104 auxiliary boosters had a greater brisance than the tetryl-loaded ones but that a heavier booster charge was required for detonation. Since such a booster charge was already available, the tetrytol-loaded auxiliary booster was considered more satisfactory than the tetryl-loaded one.


TORPEX is an explosive based on trinitrotoluene (TNT) that gave a greater blast than TNT, but was more sensitive. It was replaced by HBX or HBX-1 later in WWII. Torpex is RDX/TNT/Aluminum/Wax desensitizer. It was used in several types of torpedoes and mines. Due to it sensitivity to bullet impact, the first weapons loaded were ones for which there would be the least possibility of rifle bullet and fragment attack, namely, submarine delivered mines and torpedoes. The loading stations were advised that they must take adequate care in mixing and loading and in the handling of the loaded items. It was declared that the British had been able to handle it without incident for 2 years and that the risk was worth the advantage gained in its underwater power.


The GBU-28 contains only six hundred pounds of Tritonal. The BLU-109/B was an improved 2,000-pound-class penetrator bomb designed for attacking the most hardened targets. Its skin was much harder than that of a standard iron bomb, consisting of a single-piece, forged warhead casing of one-inch, high-grade steel. The bomb featured a 550 pound tritonal high-explosive blast warhead and was always mated with a laser guidance kit to form a laser-guided bomb. The Tritonal filling of the BLU-109/B is similar in size to the warhead of the Mk.48 series torpedo. Explosive (NEW) 535 lbs. Tritonal in the BLU-109 and 945 lbs. of Tritonal on the MK 84.

The Munitions Directorate's successful completion of the Miniaturized Munition Technology Demonstration (MMTD) Program, has provided an innovative weapon called the Small Smart Bomb. The miniaturized munition concept includes a weapon that issix feet long, six inches in diameter, and weighs only 250 pounds with approximately fifty pounds of Tritonal explosive material. The weapon is effective against a majority of hardened targets previously vulnerable only to munitions in the 2,000 pound class. The Air Force Research Laboratory's Munitions Directorate has set the baseline for small bomb development by successfully demonstrating the technology that will be used to further the development of a 250-pound class munition. Small Smart Bomb's size will allow future fighter and bomber aircraft to carry more weapons in their weapons bays.

Polynitrocubane Super Explosives are a family of new energetics. In FY96, the Army initiated the synthesis of a more powerful polynitrocubane explosive. In FY97, the Army scaled up the polynitrocubane explosive to pound level. In FY98, scale up the polynitrocubane explosive to pilot plant quantity and initiate formulation study for anti-armor warhead (Shaped Charge or explosively Formed Penetrator) loading. In FY99, conduct static warhead test using the polynitrocubane explosive to show increase in energy performance by up to 25 percent and with comparable sensitivity to LX-14.

The current winner in the most powerful explosives debate is heptanitrocubane (HpNC). It has beat out the theoretically more powerful octanitrocubane (ONC) in actual tests recently performed. ONC has only been synthesized in the last year, but it has been calculated to have the greatest density of any explosive we could make. In reality ONC does not achieve this theoretical density. Since it has existed for such a short time, researchers conclude that they simply have yet to find its most dense crystalline form. The default winner is the next best thing, HpNC. Further conjecture into nitro cubane chemistry has hypothesized at the possibility of polynitrocubane molecules which could achieve even greater densities.


The Lockerbie Case

A commentary on the case of Abdelbaset al-Megrahi, convicted of the murder of 270 people in the Pan Am 103 disaster. British Blogs

Thursday, 24 September 2009

Crown challenged to prove semtex link to Pan Am 103

[This is the headline over an article published today on the website of the Scottish lawyers' magazine The Firm. The following are excerpts.]

[A] campaign initiated by the Lockerbie Justice Group ... challenges the Lord Advocate to openly demonstrate that Pan Am 103 could have been brought down by a semtex bomb, under controlled laboratory conditions.

The group state that fabric and circuit board fragments cannot survive a semtex explosion, and accordingly the entire Crown case against Abdelbaset Ali Mohmed Al Megrahi falls. In 2007 Ulrich Lumpert of timer company MEBO released an affidavit stating he had manufactured the circuit board “evidence” relied upon by the Crown at the Zeist trial. Earlier this year a
report by Dr Ludwig de Braeckeleer concluded that the Crown’s case was “scientifically implausible”.

“The Crown theory utterly depended upon Judges believing that this white-hot sphere with a temperature of 6,800F, travelling in all available directions at 20,000mph did not scorch, never mind totally annihilate, a printed circuit board and a fabric label, which it was able to wholly detach from the shirt. Our group finds this utterly incredible,” the group said.

“We, as members of the concerned Scottish public, invite the Crown to openly demonstrate their theory under controlled laboratory conditions. Either the circuit board survives with its legible ID and soft solder, or it is annihilated in a white-hot gas. In the event of PCB annihilation, we demand a proper and independent committee of inquiry into ‘What brought this plane down?’ Will you please publicly demonstrate your theory, ... Lord Advocate?”

The challenge has been backed by Dr Hans Koechler, who observed the trial [as a UN-appointed observer] and called for a full public inquiry afterwards.

“It is highly important to address this question to the Scottish prosecutor’s office and I shall add my name to such an initiative,” he said.

“It is equally important that an explosives expert with impeccable academic credentials, ideally a University professor from a European country, endorses this initiative or confirms the basic physical facts in writing. Under this condition I can join the initiative.”

De Braeckeleer and researchers at the Centre of Explosives Technology Research in Socorro, New Mexico estimated that up to thirty pounds of explosive was needed to destroy a Boeing 747, if the explosion had occurred in the hold as the Crown claimed

“As the explosion of one pound of Semtex H inside the luggage container does not generate a blast wave sufficiently powerful to fracture the skin of the fuselage, we have little choice but to conclude that the verdict appears scientifically very implausible,” they said.

The group’s initiative is bolstered by the new testimony of former Ferranti electrical engineer Aitken Brotherston, experienced in testing circuitry for use in military applications.

“Although no doubt there have been some advances in the construction of circuit boards the predominance of boards in current use are the same as those I tested. In most cases the boards would happily catch light with a flame source similar to that of a Swan Vesta (...)

“While we did not test them to the 3000 plus degrees C temperatures of a Semtex explosion bright spot, even as an apprentice electronics engineer with Ferranti, my experience at much lower temperatures would persuade me that nothing of the circuit boards would survive that environment.

“The proposal that fragments of the board, of sufficient size to permit identification, packed with the bomb had survived a temperature environment of more than 3000 degree C in the explosion is to me just not credible.

“What it does demonstrate is the extent to which anyone promulgating that theory believes us out here in the real world to be completely stupid.”

Robert Black13:36


Grendal said...

Surely this test could be done privately, under controlled scientific conditions. I`m sure the Libyan government could be persuaded to fund it.
I still can`t believe that no test for residue was done on the timer fragment (if there was one)and the label.Could it be that a test was done and the results supressed?

25 September, 2009

sfm said...

> I still can`t believe that no test for residue was done on the timer fragment (if there was one)and the label.

I am met a "Don't be stupid!" when I tell people about this.

Imagine a presentation of a knife in the court, claimed to be used as a murder weapon. It is unthinkable, that such a knife would not have gone through all the tests in the book - fingerprints, DNA (victim's and accused's) and traces of blood.

> Could it be that a test was done and the results supressed?

That could be, but on the other hand - if the fragment was real it should have the traces, and it would be presented in court.

If it was not, it would not be sent for analysis, so most likely - and unbelievably - the fragment was never checked.

- - -

But in the end - lets say, that defense HAD asked, and prosecution had to say that it was not tested. I think it would not have had any impact. It is too plausible to believe that it is just THE timer fragment.

The prosecution would ask: Would the defense have any suggestions as of how such a fragment of a highly specialized device would end up at that place, and in that shape, if not being a part of the bomb?

That has merit too.

25 September, 2009

Nennt mich einfach Adam! said...

In court Mr. Hayes and Mr. Feraday admitted that there had been no test for explosives on the crucial electronic fragments. Of course the judges should therefore have rejected these fragments as evidence.
But, as my old friend Niccolo Machiavelli comments: Why test a component for explosive residue when you know that there is not any?

26 September, 2009

Grendal said...

“The proposal that fragments of the board, of sufficient size to permit identification, packed with the bomb had survived a temperature environment of more than 3000 degree C in the explosion is to me just not credible"
Even less credible is the fact that parts of the Toshiba User`s Manual (presumably paper)survived the 3000 degree blast.I assume no test for explosives were done on these pieces either!

26 September, 2009

Grendal said...

From the judges opinion...."The method adopted by the forensic scientists was to treat as a
high probability that any explosion damaged clothing which contained fragments of
the radio cassette player, the instruction manual, and the brown fabric-lined cardboard
partition from within the suitcase to the exclusion of fragments of the outer shell, was
within the primary suitcase." Surely a much more accurate test would have been to test for traces of explosives on the articles.I must be missing something!

By the way, I see from the judges opinion that where tests for explosives were done (on the baggage containers,I think)no control was carried out.
"Some traces appeared to be found well away from the "explosion site" but these were explained away by the experts.The traces relating to 270.1 and 270.3
indicated the presence of PETN and RDX. These are chemicals used in the
manufacture of plastic explosives, including Semtex. In cross-examination it was
suggested to him that a report by Professor Caddy presented to Parliament in 1996 on
the possible contamination of a centrifuge used at RARDE vitiated his conclusions.
However, while that report did indeed suggest that a centrifuge was contaminated with RDX, it also made clear that certain examinations carried out in the period which
included December 1988 were not affected, and in the list of such examinations was
included the examination of the Lockerbie debris carried out by Dr Douse. It was
further suggested to him that the traces disclosed peaks which were consistent with
the presence of TNT, DNT and nitroglycerin, but for the detailed reasons which he
gave in his evidence he was entirely satisfied that the peaks in question related not to
these forms of explosive but to non-explosive co-extractives. We see no reason to
doubt the conclusion to which this very experienced expert came.Finally it was
submitted that inadequate precautions were taken at the laboratory by way of the use
of control swabs of clothing and equipment to prevent the risk of distorted results
because of contamination.There was however a description both by Dr Douse and Dr
Hayes of the precautions taken to prevent contamination, and we are satisfied that
these precautions were adequate to prevent any risk that Dr Douse’s tests were
vitiated by any contamination."

26 September, 2009

sfm said...

Grendal said...
"The method adopted by the forensic scientists was to treat as a high probability...."

Surely a much more accurate test would have been to test for traces of explosives on the articles.I must be missing something

The problem is that some people believe that experts can answer everything. The belief comes from

1.- the fact that laymen can't evaluate their statements, and

2. - that some experts are willing to make far-going conclusions without basis, just like 'ordinary people'.

Nobody could ever tell if the Malta-clothing were in the suitcase with the bomb or another nearby suitcase.

It is a completely hopeless affair to have a bomb exploding in a container with size of explosive, placement of items and a composition you all know nothing about - and then later determine, with any accuracy, what items were where.

Doing _quantitative_ analysis for RDX and PETN to any point where it makes sense it far from possible.

To the question: "With what probability would you say that the mentioned items where in the suitcase with the bomb?" you could not even reach 20%.

Why? Because you'd never be able to tell the difference between the clothes in the suitcase with the bomb and the suitcases beside, on top or bottom. The suitcase-wall between the nearest suitcases disintegrates completely, instantly.

It is possible that the clothes in the suitcase would be non-existent af the explosion.

It is possible that the Toshiba recorder was in the suitcase next to the explosion.

The whole point is unscientific nonsense, one of real many in a trial loaded with far-going assumptions and wildly insufficient data and knowledge.

Science is all about making testable theories and test them.




Freely after RING magazine - the issue of September 17, 1998

Countless newspaper articles were published on SEMTEX® explosive that describe, with greater or smaller measure of authenticity and acquaintance, the properties of this explosive and speak about the cases of misuse with expertness. The myth has been successfully created during ten years on miraculous and non-detectable explosive. The explosive spun round with myths brings foreign journalists into extasy. In almost every report on explosion everywhere in the world an information appears that blames SEMTEX® for everything. Hysteria about SEMTEX® got to the point that in Great Britain the words SEMTEX® and plastic explosive are, to some extent, synonymum. In the Ring magazine the article was published in 1998 with the above given title that tried to put the most widespread mistakes right.

At a series of terrorist explosions abroad SEMTEX® is reported as a common denominator till nowadays. However, no expert can say a few hours after explosion, what was the explosive involved. Serious sources state that no SEMTEX® has ever been used in the U.S.A. and that in Great Britain the use of this plastic industrial explosive has been proved in five per cent of all cases only. The misuse of explosive as well as any other industrial product cannot be influenced by the producer. There are thousands of users of various explosives in the world and, according to the police experience, it is just them the stolen explosives come from. The more often SEMTEX® has been written about , the more mistakes have appeared.

The first mistake: the Presidential one
Many years the fact has been spoken about, that from 1974 to 1981 ( export into risky countries was prohibited in those times) one thousand tons of SEMTEX® was exported to Libya, as mentioned in one interview by the President Václav Havel in 1990. Even if it was not Synthesia to trade with this explosive in those times, but foreign trade companies, the experts have been wagging their heads in astonishment over this number up till now.
According to all information ascertained, during the whole time of production 690 tons of plastic explosives was produced for export.

The second mistake: the strongest explosive
The strongest plastic explosive in the world. A few grams is enough to destroy an aircraft. Explosive SEMTEX® is not exceptional in its performance, it is on the same level as a series of foreign explosives of its category. SEMTEX® differs from other plastic explosives only by having the binder system (ensuring long-term plasticity) of different composition.

The third mistake: it will last forever
Popularity of plastic explosives consists in their capability to be shaped well. They are safe to store. SEMTEX® is usually said to last forever, which is also the case of the Libyan shipment. It follows from the long-term testing, that in usual storage environment the plasticity will last for several years. But according to available information from Africa, in extreme temperature conditions SEMTEX® loses its plasticity, gets hard and disintegrates.

The fourth mistake: cannot be detected
Synthesia Semtín started marking of explosives according to international agreements in 1991, it means even before the then Czechoslovakia acceded to the convention on marking and seven years before the convention entered into force. At present time SEMTEX® can be detected using technical means. The technique got to the point, that it is possible to detect the original, not marked SEMTEX®. The marking that would identify the explosive with certainty even after explosion is not commonly practised by the world producers of plastic explosives and by Explosia a.s. either.

The fifth mistake: the only producer
Plastic explosives are produced in a number of advanced countries. C-4 explosive is of American origin, other countries producing these explosives are Russia, Great Britain (PE-4), France, Yugoslavia, Monte Negro, Greece, Poland...
It is remarkable that as early as 1995 the Czech Police detained three men with several tens kilogram of American explosive C-4.

The sixth mistake: there is no terror without SEMTEX®
Trading with plastic explosives on the black market is dangerous. Today the terrorists know that explosive can be produced of practically anything in a relatively simple way. You can be sure to find instruction how to produce effective explosive from industrial fertiliser on the Internet. Even a Jules Verne books lover can learn in one of them how to prepare gunpowder.

The seventh mistake: Explosia a.s. will become bankrupt
Popular statement is, that the moment when production of SEMTEX® stops will bring about the end of Explosia a.s. All types of SEMTEX® explosive represent only a fraction of per cent of all produced explosives and propellants.

The eighth mistake: the inventor of SEMTEX®
Explosion in the spa building in Jeseník a few years ago became the basis of romantic story: the inventor of SEMTEX® explosive, Bohumil Šole, remorseful about what his invention brought about, committed suicide. The reality is, however, quite different. Production of SEMTEX® started in Synthesia in 1964. In the sixties, when Mr. Šole was already working here he was injured when explosive exploded not far from him and since then he suffered from depressions as a result of that injury. In the eighties he participated in testing of aircraft destruction for the Czechoslovak Army and Ministry of Interior of the Czechoslovak Republic. It was him who wanted to patent aircraft destruction by means of plastic explosives. In the end of the eighties he had some difficulties with StB (State Secret Police) that lead to a trial in the end of 1989, later the verdict was annuled to the full extent. Mr. Šole worked in the Sales Department of the company till 1989. By no means we can contest his enormous experience in the field of explosives. He, however, was not a member of the team that developed SEMTEX®.

The ninth mistake: Fabulous prices
Legends go about fabulous prices for one kilogram of SEMTEX® explosive. In every case it is, however, a matter of absurd and stilted figures. Unfortunately, their presentation in the media can be one of the motives for stealing SEMTEX® from the Army depots, or, for amateur production according to more or less credible recipes obtained from Internet.

The tenth mistake: Production of SEMTEX® is not secured
"Sure" information appear in press from time to time, that the state or producer are incapable of securing production of SEMTEX® explosive, possibly of making impossible its illegal export. Last year a "sure" information appeared in foreign press on getting of one "also journalist" directly into production buildings where he walked freely between "bubbling vessels with semtex". The legend of "infernal explosive" seems to be very inspiring.

And what will be the next published mistakes? The time and "serious" media will show us.













Class Vocabulary


555 timer

A semiconductor device that controls various modes of on/off states in electrical systems. The 555 timer is one of the most widely used types of integrated circuits.


The process of increasing the size or strength of a signal.

amplifier gain

The ratio of an output signal's amplitude divided by the input signal's amplitude. Amplifier gain measures the degree to which a signal has been strengthened.


To increase the size or strength of a signal.


The maximum height or depth of a sine wave.


A logic function where both A and B must be true to trigger C. AND employs a logic that works similar to a series circuit.


The positive terminal of an electric current flow.


An element used to dope silicon to create an N-type semiconductor.


A mode in which a 555 timer produces a continuous string of on/off pulses at a preset frequency.

avalanche breakdown

A process that occurs in a diode when high voltage causes free electrons to travel at high speeds, colliding with other electrons and knocking them out of their orbits. The result is a rapidly increasing amount of free electrons.

avalanche diode

A specialized diode that acts as a relief valve for excess voltage. Avalanche diodes are sometimes used in combination with Zener diodes.


The input control terminal of a semiconductor device. Also called a gate.

bipolar transistor

A three-layer semiconductor device that can conduct current in either direction. Bipolar transistors provide current gain and voltage amplification in a circuit.


A mode in which a 555 timer changes from 1 to 0 or from 0 to 1 when current is applied. The timer will remain in the transitioned state until it receives a new input.


An element used to dope silicon to create a P-type semiconductor.


A condition that occurs when maximum reverse voltage in a diode is exceeded. Breakdown will cause a diode to fail and pass a large amount of current in the reverse direction.

breakdown voltage

A term used to describe the level of AC or DC voltage that results in the failure of a semiconductor device.


The ability to store an electrical charge.


The negative terminal of an electric current flow.


Complementary metal-oxide semiconductor. The CMOS IC is the most popular type of digital IC because of its low power usage and high immunity to noise.


The output terminal of a semiconductor device. Also called a drain.

common base

A transistor amplifier in which the circuit shares the base terminal for both inputs and outputs.

common collector

A transistor amplifier in which the circuit shares the collector terminal for both inputs and outputs.

common emitter

A transistor amplifier in which the circuit shares the emitter terminal for both inputs and outputs.

complementary metal-oxide semiconductor

CMOS. The most popular type of digital IC because of its low power usage and high immunity to noise.


To change the amplitude or frequency of an analog signal.

depleted region

The part of a PN junction in which there are no electrons or holes. The depleted region prevents current from flowing.


Diode alternating current switch. A DIAC can conduct current in either direction, but not until breakdown voltage has been exceeded.

digital IC

Digital ICs process only on/off signals. These devices can be found in microprocessors, memory chips, and microcomputers.


A semiconductor device that acts as a one-way valve for electrical current.

diode alternating current switch

DIAC. A semiconductor device that can conduct current in either direction, but not until breakdown voltage has been exceeded.

diode array

A group of diodes arranged in a highly organized manner. Diodes are combined into arrays for greater efficiency and reliability.


Dual-inline package. A popular type of integrated circuit packaging that has two rows of external connecting terminals.


The process of changing the conductive properties of silicon by adding trace amounts of other elements.


The output terminal of a semiconductor device. Also called a collector.

dual-inline package

DIP. A popular type of integrated circuit packaging that has two rows of external connecting terminals.

electrostatic discharge

Static electricity that can damage integrated circuits.


The terminal in a semiconductor device that is connected to the source supply of voltage. Also called the source.


Electrostatic discharge. Static electricity that can damage integrated circuits.


Field effect transistor. A FET is a semiconductor device that outputs current in proportion to its input voltage. FETs use a small amount of control current to regulate a larger output current.

fiber optic

A filament made of thin, flexible glass or plastic through which light is transmitted. Optical fibers are bundled into groups to form fiber optic cable.

field effect transistor

A semiconductor device that outputs current in proportion to its input voltage. FETs use a small amount of control current to regulate a larger output current.

flat pack

A type of integrated circuit packaging that is extremely thin and flat. A quad flat pack or QFP has leads projecting from four sides.

flip-flop circuit

A circuit that changes from 1 to 0 or from 0 to 1 when current is applied.

forward bias

A condition in which a PN junction allows current to flow in one direction only.

full-wave rectification

A type of current conversion that uses both parts of the AC sine wave, both positive and negative, to produce a DC output with a single polarity.


The input control terminal of a semiconductor device. Also called the base.

gate current

A small amount of forward-biased current in the middle PN junction of an SCR that controls a larger amount current flowing through the SCR.

half-wave rectification

A type of current conversion that uses only one half of an AC waveform to convert into intermittent DC. This can be the positive half or negative half of an AC wave, depending on how the diode is connected to the circuit.

holding current

The minimum current which must pass through a semiconductor device in order for it to remain in the ON state.


An extra opening in the outer orbital shell of an atom into which an electron can move.


Integrated circuit. A miniaturized electronic circuit that combines a variety of components like transistors, resistors, capacitors, and diodes all into one incredibly small piece.


The International Electrotechnical Commission. An international organization that prepares and publishes all standards for electrical, electronic, and related technologies.


Resistance to current flow in an AC circuit.

integrated circuit

A miniaturized electronic circuit that combines a variety of components like transistors, resistors, capacitors, and diodes all into one incredibly small piece.

intrinsic semiconductor

A type of semiconductor that has a low level of electron movement at any temperature above 0°C (32°F). Silicon is an intrinsic semiconductor.


Junction field effect transistor. A solid state device that can be used as an electronically controlled switch.

leakage current

The amount of current required to keep a device active when it is not operating. Also known as load current and residual current.


Light emitting diode. A semiconductor device that emits a narrow spectrum of light in a forward direction.

logic gate

A programming function that processes true and false signals.

low current drop

A condition that occurs when the current falls below the minimum value required to operate a semiconductor device.


A mode in which a 555 timer produces a single pulse for a preset amount of time in response to an input.


Metal oxide semiconductor field effect transistor. A type of transistor that is controlled by voltage rather than current.


A device that controls various modes of on/off states in electrical systems. A multivibrator behaves like a pendulum moving back and forth, or a ball bouncing up and down.


A logic function where both A and B must be false to trigger the output. If one input is present, the output will not be turned on.


A logic function where the output will be triggered if neither A nor B are present.


A logic function where the output will not be triggered if a specified input is present.

n-type semiconductor

A type of semiconductor that moves current by creating extra electrons that are easily excited into movement.


A series of timer instructions that creates a delay for only one scan.


A logic function where the output is triggered if either A or B are true. OR works similar to a parallel circuit.


A device that produces a continuous string of on/off pulses at a preset frequency.


Printed circuit board. Semiconductor devices are often mounted on PCBs because the electrical paths on a PCB are perfect for the needs of most semiconductors.

PIN diode

A specialized diode that has a layer of intrinsic semiconductor material between the P and N materials. PIN diodes are also used as photodetectors.

PN junction

The area in a semiconductor where P-type and N-type materials are located next to each other. A PN junction allows current to flow in one direction only.


Having a positive or negative charge.

printed circuit board

PCB. Semiconductor devices are often mounted on PCBs because the electrical paths on a PCB are perfect for the needs of most semiconductors.

p-type semiconductor

A type of semiconductor that moves current by creating holes for the movement of valence electrons.

pulsating DC

A type of DC current in which half of the original AC signal wave is blocked, so that the resulting DC signal rises from zero to a maximum, and then returns to zero.


Quad flat pack. A type of integrated circuit packaging that is extremely thin and flat. A QFP has leads projecting from four sides.

quad flat pack

A type of integrated circuit packaging that is extremely thin and flat. A quad flat pack or QFP has leads projecting from four sides.


A device that converts AC into DC.


To convert into direct current.

reverse bias

A condition in which a PN junction does not allow current to flow.

reverse breakdown voltage

The amount of reverse bias that will cause a diode to break down and conduct in reverse.

reverse firing

A method of turning off an SCR by applying negative voltage to the gate. Reverse firing requires a high amount of gate current.


A three-layer NPN or PNP arrangement of semiconductor material.

Schottky diode

A specialized diode used in the electronics industry and in radio frequency applications because of its fast switching speed and high frequency capability.


A solid state switching device that turns current on and off. SCRs use a small amount of current to switch hundreds of amps without being damaged.


A solid state device that is less conductive than a conductor, but more conductive than an insulator. The most common semiconductor material is silicon.


The transmission of electrical signals.


An element from which almost all semiconductors are made.

silicon controlled rectifier

A solid state switching device that turns current on and off. SCRs use a small amount of current to switch hundreds of amps without being damaged.

silicon dioxide

A glass-like material that is naturally an excellent insulator. Silicon dioxide is used as the gate insulating material in a MOSFET.

single-phase rectifier

A semiconductor device that converts single-phase AC into DC. In a single-phase rectifier, the sine waves produced by the AC power supply reach their peak at 90° simultaneously.

solid state

Purely electronic with no moving parts.


The terminal in a semiconductor device that is connected to the source supply of voltage. Also called the emitter.


The surface or medium that serves as a base for other materials or components.


The process of making or breaking an electric circuit, or selecting between multiple circuits.


A connecting point in a circuit to which a wire can be attached to connect a component.

three-phase electric power

A type of AC power that is generated with three waveforms that are not in phase with each other.

three-phase rectifier

A type of rectifier that uses a three-phase AC electric power source to produce a relatively smooth DC. Three-phase rectifiers provide much smoother DC output voltage than single-phase rectifiers.


A three-terminal semiconductor switching device. The two main types of thyristors are SCRs and TRIACs.

TO package

Transistor-outline package. A type of integrated circuit packaging that is cylindrical in shape and looks like a little can.

TO-5 can

A commonly used TO package.


A solid state device that can be used either as an amplifier or as a switch. There are two basic types of transistors: bipolar and field effect.


A type of integrated circuit packaging that is cylindrical in shape and looks like a little can.


Triode alternating current switch. A gated switching device that will conduct current in either direction.

triode alternating current switch

TRIAC. A gated switching device that will conduct current in either direction.


Unijunction transistor. A voltage-controlled switch that controls current.

unijunction transistor

UJT. A voltage-controlled switch that controls current.

valence electron

An electron found in the outermost orbit of an atom.

varactor diode

A specialized diode that changes its level of capacitance depending on the level of reverse bias applied to the diode. Also known as a varicap diode.

varicap diode

A specialized diode that changes its level of capacitance depending on the level of reverse bias applied to the diode. Also known as a varactor diode.

zener diode

A specialized diode that is used as a voltage regulator. Zener diodes maintain voltage at a constant, predefined value when they are subjected to reverse voltage.


Ben Palacio TACT OFFICER – IN- TRAINING, 10/15/2009  - Instructor: Patrick Hardy, BAO

TeachBack Verbage


Hello folks, please come closer and tell me what you see.

Okay,  Here  we have a bomb in the bag. The following components are present:

1.    Here is the POWER SOURCE

a.      The power source here is a 9 volt.

b.      The power source of choice is often a 9 volt battery but could be other types. power  source already present in everyday device or devices doubling as timer / switch such as cell phones  may be adopted.

c.      Other power sources could be capacitors, e-cells, button cell batteries connected in series etc.. ..  .


2.    Here is the SWITCH/TIMER

a.      The switch here is toggle type switch.

b.      Once I throw the switch into the on position it completes the circuit and allows sufficient volts which must be at least 3 volts or about 8 amps to reach and incite the initiator/detonator.

c.      The switch could be anything within the imagination of the terrorist and sometimes a 555 type timer or SCR allowing for pre-setting the time.


3.      Here is the FUSE / INITIATOR / DETONATOR

a.     The fuse/initiator/ detonator being used here is a TATP filled electric detonator.

b.    The initiator has been inserted into the well of this cheese looking block of  TNT.

c.     The fuse serves 2 purposes: it controls the precise instant of detonation and it starts the chemical or physical action necessary  to "blow-up"  or propergate its  small energy  into a larger EXPLOSION of the of the main charge. 


4.    Here is the MASS / EXPLOSIVE

a.      The main charge used here is a block TNT [TNT [trinitrotoluene]

b.       TNT is the most commonly used explosives. TNT is relatively safe to handle but its chemical composition provide the destructive blast effect of a bomb and is a high explosive.  

c.      Bombs are constructed so that they will not explode until the fuse has been armed


If there are no questions can anyone explain the main points I’ve just explained.