Composition C

The Composition C family is a family of related US-specified plastic explosives consisting primarily of RDX. All can be moulded by hand for use in demolition work and packed by hand into shaped charge devices. Variants have different proportions and plasticisers and include composition C-2, composition C-3, and composition C-4.

The term composition is used for any explosive material compounded from several ingredients. In particular, in the 1940s the format "Composition <letter>" was used for various compositions of the (relatively) novel explosive RDX, such as Composition B and other variants.

The original material was developed by the British during World War II, 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. 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, nitrocellulose and a mixture of nitroaromatics produced during the manufacture of TNT (containing trinitrotoluene, dinitrotoluene and mononitrotoluene), 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, 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.)

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