Detection of Semtex Plastic Explosives

Semtex is one of the commonly used forms of plastic explosives. Plastic or Putty explosives are handmade explosives. They are flexible in nature and easy to hand mold them. These explosives are mostly composed of 80 percent explosive material and 20 percent soft plastic with temperature varying between -22 to 129 degree fahrenheit. 

In the early 1900’s at the time of world war I is when plastic explosives first came into use, they were called nitrols. Back then it was considered as the most potent plastic explosive. World War II was when plastic explosives like explosive 808 came into the limelight, it was considered to be one of the most sought-after explosives of that time. 

As World War II kept progressing newer versions of plastic explosives kept being developed with higher RDX components. From Gelignite being the first putty explosive to Semtex the commonly used plastic explosive, plastic explosives are useful both in commercial and military purposes. 

Coming to the uses of plastic explosives, these kinds are useful in various purposes. Engineers use plastic explosives for demolishing purposes as well as at mining sites to blast bigger obstacles. Military engineers work in shaping and forming plastic explosives in order to use them for military warfare purposes. 

Commercially plastic explosives are used in metal industries for either the cutting work or the hardening work depending on the composition of the explosive make. With high explosive shock waves and higher density, these make an ideal option for industrial cutting purposes. 


Different nations design and manufacture different kinds of Plastic explosives depending on the level of usage and purpose. For instance Germany manufactures Seismoplast 1, whereas Switzerland manufactures Plastex. Australia, the PE4’s; USA, the Composition C4. UK manufacturers both the PE variant as well as Composition C4, with Sweden and Netherlands manufacturing NHS711 and Knaverit S1 respectively. Semtex is the produce of the Czech Republic, Israel, and UK.

More about Semtex

Semtex is a widely used plastic or putty explosive discovered in the Czech Republic in the early ‘60s. In its initial days, Semtex was widely used, well-noted names associated with the usage of Semtex explosives are Vietnam Army in the Vietnamese War and the Ireland Army.

After being identified as the easily available explosive associated with many terrorist activities the export of Semtex was cut short to a limited number and is now governed by political bodies. However, over a period of time, to be specific from the early ‘90s microchips were started to be implemented in the semtex explosives in order to easily detect and track their usage. 

Types of Semtex Plastic Explosives

Semtex comes in three variants depending on the composition of various materials. The three variants being- Semtex 1A, Semtex H, Semtex 2P.

  • Semtex 1A
    This kind of plastic explosive is commonly used for mining purposes. Semtex 1A is made out of- 76% Penthrite, 4.6% RDX, 9.4% Styrene Butadiene Rubber as a binder agent, 9% Plasticizers, 0.5% Antioxidant and 0.5% Sudan IV as a dye or pigment.
  • Semtex H
    This kind of plastic explosive is commonly used as shock hardeners in order to harden and strengthen alloys and metals. Semtex H is made out of- 40.9% Penthrite, 41.2% RDX, 9% Styrene Butadiene Rubber as a binder agent, 7.9% Plasticizers, 0.5% Antioxidant and 0.5% Sudan I as a dye or pigment.
  • Semtex 2P
    These kinds of plastic explosives are commonly used as detonators for demolishing purposes. Semtext 2P is made out of- 58.45% Penthrite, 22.9% RDX, 9.2% Styrene Butadiene Rubber as a binder agent, 8.45% Plasticizers, 0.5% Antioxidant and optional pigment.

Ways to detect Semtex Plastic Explosives

Semtex Explosives can be detected using multiple ways, a couple of them are explained below-

  1. Electronic Detectors
    Chemical resistive detecting sensors are used to detect Semtex Plastic Explosives, these detectors are small in size, consume way lesser energy and are quick at detecting explosives.
  2. X Rays
    Typically used at baggage counters and xray screenings. X-Rays are helpful in detecting the elements that go into producing an explosive. X-Ray based technology to detect explosives are commonly set up at airports. 
  1. Dogs
    Dating back to the mid 1900’s, one of the earliest methods of detecting explosives is by letting dogs sniff the explosive’s scent. Dogs are trained for this purpose as they come useful due to their sensitive noses, communicating in their trained way of response.
  2. Color Reactions or Colorimetrics
    This method is right out of a chemical laboratory. suspected material is coated with a chemical reactant, upon the change of color of the reactant explosives are detected. The chemicals that go into composing an explosive reacts to the chemical coated to detect.
  3. Honey Bees
    Lesser popular and limited usage approach is using honey bees to detect explosives. Although they are proven more potential than dogs in sniffing explosives out. Honeybees are specifically trained for these purposes.
  4. Scent Detection Devices
    These are mainly used to detect bigger size explosives or multiple explosives set in vast expanses. These equipment help in tracing explosive materials without sampling them. They use a technology called machine olfaction which replicates the human sense of smell in an automated machine format. 
  5. Spectrometry
    Spectrometry is an analytical technique which helps in separating compositions of elements both in liquid form and gaseous form. This way the ratios of compounding elements are identified thus detecting drugs and explosives. Mass spectrometry devices are being used by nations such as the United States, European nations and Israel.
  6. Neutron Activation Analysis
    Neutron Activation Analysis takes place with the usage of specially crafted equipment that bombard the sample with neutrons to understand the ratios between hydrogen, nitrogen and chlorine atoms i.e. identifying the chemical composition of the sample.
  7. Nanotechnology
    Nanotechnology can be used to detect explosives of liquid or vapour form. These liquid or vapour explosives are let flow over a silicon chip built out of minute nano wiring which helps detect the explosive. Silicone chip on contact with the explosive reacts to the material that goes into composing these explosives, hence detecting.  

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