Composition B

Composition B
Ercan Seyhan and Salih Cengiz · CC BY 4.0 · source
Name	Composition B
Type	High explosive
Used by	United States, NATO, others
Wars	World War II, Korean War, Vietnam War
Filling	RDX, TNT, wax
Detonation	Blasting cap

Composition B. It is a high explosive mixture consisting primarily of RDX and TNT, with a small addition of wax as a desensitizing agent. Developed during the early stages of World War II, it became a standard-issue explosive for the United States Armed Forces and its NATO allies. The formulation offers a powerful blast with reliable stability, making it suitable for a wide array of munitions and demolition tasks.

Composition and formulation

The standard formulation, often designated as **Composition B**, is approximately 60% RDX and 40% TNT, with about 1% wax added. The RDX provides high brisance and detonation velocity, while the molten TNT acts as a binder and lowers the mixture's sensitivity. The wax, typically paraffin wax, coats the RDX crystals to further reduce friction sensitivity and improve safety during handling and processing. Variations, such as **Composition B-3** or **Composition B-4**, adjusted the ratios slightly or used different wax types to optimize performance for specific manufacturing processes or climatic conditions encountered from the Arctic to the Pacific Theater.

History and development

The development was driven by urgent needs during World War II, particularly following the Tizard Mission, which shared advanced British explosive research with the United States. Scientists at the Explosives Research Laboratory in Bruceton, Pennsylvania, and other facilities like the Naval Surface Warfare Center worked to adapt the powerful but sensitive RDX into a safer, castable form. This work built upon earlier German work with Hexogen and was influenced by the British use of similar mixtures like Cyclotol. Its adoption was rapid, seeing extensive use in ordnance such as the M7 grenade and artillery shells throughout campaigns including the Battle of Normandy and the Battle of Okinawa.

Properties and characteristics

It is a solid, castable explosive with a density typically around 1.65 g/cm³. It has a high detonation velocity, approximately 8,000 meters per second, and a detonation pressure superior to pure TNT. The addition of TNT gives it a relatively low melting point, allowing it to be safely melted and poured into shell casings. While less sensitive than pure RDX, it is more sensitive to impact and friction than TNT alone, necessitating careful handling procedures. Its performance is stable across a wide temperature range, though it can exude TNT or form cavities if subjected to repeated thermal cycling, a phenomenon studied at facilities like the Los Alamos National Laboratory.

Military and civilian use

Its primary use has been in military applications, filling a vast array of munitions for the United States Department of Defense. It was the explosive fill for standard general-purpose bombs, artillery shells like those for the M101 howitzer, land mines such as the M15 mine, and shaped charges in weapons like the M72 LAW. Beyond bulk explosives, it was also used in demolition blocks for engineers. In civilian sectors, its use is highly restricted but parallels military demolition for large-scale projects like quarrying or the controlled demolition of structures, often under the oversight of agencies like the Bureau of Alcohol, Tobacco, Firearms and Explosives.

Safety and handling

Standard safety protocols for high explosives must be strictly observed. It is classified as a Division 1.1 explosive under United Nations recommendations, indicating a mass explosion hazard. Storage must be in approved magazines, away from sources of heat, flame, or shock. Personnel require training per regulations from the Department of Defense or Occupational Safety and Health Administration. Specific hazards include the potential for TNT exudation, which can form more sensitive crystalline surfaces, and its toxicity, as TNT exposure can cause conditions like cyanosis. Disposal is typically by controlled detonation by units like the Explosive Ordnance Disposal teams.

Category:Explosives Category:Military explosives Category:World War II explosives