Composition C
Encyclopedia
The Composition C family is a family of related US-specified plastic explosive
Plastic explosive
Plastic explosive is a specialised form of explosive material. It is a soft and hand moldable solid material. Plastic explosives are properly known as putty explosives within the field of explosives engineering....

s consisting primarily of RDX
RDX
RDX, an initialism for Research Department Explosive, is an explosive nitroamine widely used in military and industrial applications. It was developed as an explosive which was more powerful than TNT, and it saw wide use in WWII. RDX is also known as cyclonite, hexogen , and T4...

. All can be moulded by hand for use in demolition work and packed by hand into shaped charge
Shaped charge
A shaped charge is an explosive charge shaped to focus the effect of the explosive's energy. Various types are used to cut and form metal, to initiate nuclear weapons, to penetrate armor, and in the oil and gas industry...

 devices. Variants have different proportions and plasticisers and include C-2, C-3, and C-4
C-4 (explosive)
C4 or Composition C4 is a common variety of the plastic explosive known as Composition C.-Composition and manufacture:C4 is made up of explosives, plastic binder, plasticizer and usually marker or odorizing taggant chemicals such as 2,3-dimethyl-2,3-dinitrobutane to help detect the explosive and...

.

The term composition is used for any explosive material compounded from several ingredients. In particular, in the 1940s the format "Composition " was used for various compositions of the (relatively) novel explosive RDX, such as Composition B
Composition B
Composition B, colloquially "comp B", is an explosive consisting of castable mixtures of RDX and TNT. It is used as the main explosive filling in artillery projectiles, rockets, land mines, hand grenades, sticky bombs and various other munitions...

 and other variants.

The original material was developed by the British during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, and standardised as Composition C when introduced to US service. This material consisted of 88.3% RDX and a mineral oil-based plasticiser and phlegmatiser
Phlegmatized
Phlegmatized is a term applied to an explosive that has had an agent added to stabilize or desensitize it. Sometimes this is desirable, to enable handling or to reduce the rate of combustion. Typical phlegmatizing agents include wax, paper, water, and paraffin. These agents are nearly always...

. It suffered from a relatively limited range of serviceable temperatures, and was replaced by Composition C-2 around 1943.

Composition C-2 contained a slightly smaller proportion of RDX, but used an explosive plasticiser, which contained tetryl
Tetryl
2,4,6-Trinitrophenylmethylnitramine commonly referred to as tetryl is a sensitive explosive compound used to make detonators and explosive booster charges....

, nitrocellulose
Nitrocellulose
Nitrocellulose is a highly flammable compound formed by nitrating cellulose through exposure to nitric acid or another powerful nitrating agent. When used as a propellant or low-order explosive, it is also known as guncotton...

 and a mixture of nitroaromatics produced during the manufacture of TNT (containing trinitrotoluene, dinitrotoluene
Dinitrotoluene
2,4-Dinitrotoluene or Dinitro is an organic compound with the formula C6H32. This pale yellow crystalline solid is well known as a precursor to trinitrotoluene but is mainly used in the polymer industry....

 and mononitrotoluene
Mononitrotoluene
Mononitrotoluene, or methylnitrobenzene or nitrotoluene , is a group of 3 organic compounds, a nitro derivative of toluene...

), and a trace of solvent. While Composition C-2 had a much wider serviceable temperature range than Composition C, it could not be stored at elevated temperatures. Consequently it was replaced around 1944 by Composition C-3.

Composition C-3 was very similar to Composition C-2, but removed the solvent and varied the exact proportions of plasticisers to improve high temperature storage. It is a yellow, putty-like material. It remained a service item through the Korean War
Korean War
The Korean War was a conventional war between South Korea, supported by the United Nations, and North Korea, supported by the People's Republic of China , with military material aid from the Soviet Union...

, but had marginal plasticity at the very low temperatures encountered in Korean winters, and was significantly toxic, including by vapour and skin absorption. The velocity of detonation is about 7600 m/s (25,000 feet per second.)

Research on a replacement for C-3 was begun prior to 1950, but the new material, Composition C-4
C-4 (explosive)
C4 or Composition C4 is a common variety of the plastic explosive known as Composition C.-Composition and manufacture:C4 is made up of explosives, plastic binder, plasticizer and usually marker or odorizing taggant chemicals such as 2,3-dimethyl-2,3-dinitrobutane to help detect the explosive and...

, did not begin pilot production until 1956. It was so successful that it remains in service as of 2011.
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