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Amatol is a highly explosive material made from a mixture of TNT and ammonium nitrate. Amatol was used extensively during the First World War and the Second World War. It was eventually replaced with alternatives such as Composition B, Torpex and Tritonal etc.

Amatol was generally used as an explosive in military weapons such as aircraft bombs, shells and naval mines. Amatol exploits the synergy between TNT and Ammonium nitrate: TNT has a high detonation velocity and good brisance, but is comparatively expensive and complex to manufacture and is also deficient in oxygen. This oxygen deficiency can be seen from the black smoke residue from a pure TNT explosion. When compared to TNT, ammonium nitrate has a fairly low detonation velocity and correspondingly low brisance, but is extremely cheap and easy to manufacture. More importantly it contains a surplus of oxygen which TNT can use during detonation. Depending on the ratio of ingredients used, Amatol leaves a residue of white or grey smoke after detonation.

Amatol allowed existing supplies of TNT to be "padded out" considerably, with little reduction in the destructive power of the final product - so long as the amount of TNT in the mixture did not fall below 60%. These were highly attractive features during major wars, when there was an insatiable demand for explosives.

Typical ratios of TNT to Ammonium Nitrate (by weight) for military Amatol are as follows:-

• 80/20
• 60/40
• 50/50
• 20/80

The Amatol production process is very simple - another reason why it was so popular during major conflicts: TNT is gently heated until it melts, acquiring the physical characteristics of a syrup. Then the correct weight ratio of powdered ammonium nitrate is added and mixed in. Whilst this mixture is still in a molten state, it is poured into empty bomb casings and allowed to cool and set solid.

The colour of Amatol ranges from off-white to slightly yellow or pinkish brown, depending on the mixture used, and remains soft for long periods of storage. It is also hygroscopic, which complicates long-term storage. It should not be stored in containers made from copper or brass, as it can form dangerous compounds. It is relatively stable, but may be detonated by severe impact. Primary explosives such as Mercury fulminate were often used as a detonator, in combination with an explosive booster charge such as tetryl.

In addition to aircraft bombs, Amatol was used in the warhead for the German V1 flying bomb, as well as the V-2 rocket. Additionally, the British X class midget submarines which planted explosive charges beneath the German battleship Tirpitz in September 1943 used "saddle charges" containing four tonnes of Amatol.

Amatol is rarely encountered today, except in legacy munitions or unexploded ordnance. However, a form of Amatol still exists under a different name - Ammonite. Ammonite is a civilian explosive, generally comprising a 20/80 mixture of TNT and Ammonium Nitrate. Typically, it is used for quarrying or mining purposes. It is a popular civilian explosive in Eastern Europe and China.

Because the proportion of TNT is significantly lower than in its military counterpart, Ammonite has much less destructive power. However, given the particular purposes for which ammonite is used, this is not an problem. In general, a 30 kilogram charge of ammonite is roughly equivalent to 20 kilograms of TNT.

• Ammonal

• Amatol. A former World War I munitions factory, located in Mullica Township, NJ. Retrieved on 2006-05-14.