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An examination of the precursor chemicals found within IEDs

Report by Brigadier Gareth Collett CBE CEng MSc BSc (Hons) FIExpE

Read the full report here

Taliban weapons cache containing bomb-making material, homemade explosives, and IEDs. Afghanistan, 2012. Department of Defence (CC BY-NC 2.0).


Home Made Explosive (HME) is an energetic material produced from precursor chemicals that have been physically mixed or combined in a chemical reaction. Production often requires the use of other chemicals to synthesize the process, or to act as catalysts.

Explosives can be single compounds or mixtures and in the context of HME, comprise a fuel and oxidizer. When initiated by a suitable stimulus, these fuels and oxidizers deflagrate (burn rapidly) or detonate, dependent upon the ‘work’ required on the surroundings (such as blast, fragmentation, or heat).

HME is generally used when the effective control of military and commercial explosives is in force. To the international community HME is a chameleon – it can exist as loose or compacted powder, as an emulsion, gel or plasticine, as a free-flowing liquid or a fine powder dispersed in the air. It can be prepared well in advance or mixed prior to use. One issue facing all States is the dual-use nature of most precursors considered in the manufacture of IEDs. This makes regulation problematic.

HME has been used in military and commercial explosive engineering applications for over a millennium, but the last 50 years have seen it metastasize in IEDs for the following reasons:

  • HME can be made from freely available precursor materials, which are not adequately policed;
  • Supply chain analysis determines what perpetrators decide to use in IEDs and is a result of the:
    • successes achieved in moving towards a mine free world;
    • improved controls over access to military and commercial explosives in States with strong institutions;
    • inability of weakened institutions to manage security of their ordnance, munitions and explosive stockpiles;
  • The internet provides ready access to technology and instructions on how to use it;
  • The sophistication of an IED lives within the imagination and the capability of the bomb maker; and
  • The lack of discrimination offered by an IED and its very subversive nature shatters the soul of any community exposed to it.

Precursor chemicals come in many forms and have a wide variety of applications. Examples include acetone, ether, glycerine, nitric acid, sulphuric acid, toluene, and urea. Some chemicals such as potassium permanganate and sodium nitrate appear on the World Health Organisation (WHO) list of essential medicines, whilst others such as sulphuric acid sit atop the world’s most manufactured chemicals given their importance to industry. It is therefore impractical and financially unviable to impose a ‘blanket ban’. Precursors can also be found in retail stores, our homes or in specialist applications. Explosives derived from such chemicals pose a considerable threat and on a TNT equivalency basis [1] can be 0.3 to 1.63 times as powerful (see Figure 1).

Report continues:

Chapter 2: History

Chapter 3: Precursor use in IED Manufacture

Chapter 4: The Regulation

Chapter 5: Analysis

Chapter 6: Future Trends

Chapter 7: Conclusion

Chapter 8: Case Studies and Annexes

Read the full report HERE