Editing Cordite (section)

== Formulations ==
It was quickly discovered that the rate of burning could be varied by altering the surface area of the cordite. Narrow rods were used in small-arms and were relatively fast burning, while thicker rods would burn more slowly and were used for longer barrels, such as those used in artillery and naval guns.{{Citation needed|date=January 2021}}

=== Cordite (Mk I) and Cordite MD ===
The original Abel-Dewar formulation was soon superseded, as it caused excessive [[gun barrel]] erosion. It has since become known as ''Cordite Mk I''.{{Citation needed|date=January 2021}}

The composition of cordite was changed to 65% guncotton, 30% nitroglycerin (keeping 5% petroleum jelly), and 0.8% acetone shortly after the end of the [[Second Boer War]]. This was known as ''Cordite MD'' (modified).<ref>Britannica, The Editors of Encyclopaedia. "cordite". Encyclopedia Britannica, 13 Apr. 2017, https://www.britannica.com/technology/cordite {{Webarchive|url=https://web.archive.org/web/20211229154751/https://www.britannica.com/technology/cordite |date=29 December 2021 }}. Accessed 29 December 2021.</ref>

Cordite MD cartridges typically weighed approximately 15% more than the cordite Mk I cartridges they replaced, to achieve the same muzzle velocity, due to the inherently less powerful nature of Cordite MD.<ref>Example : BL 6-inch Mk VII gun : 20 lb cordite Mk I, 23 lb cordite MD. Table 8 in [[Treatise on Ammunition]] 1915.</ref>

=== Cordite RDB ===
During World War I, acetone was in short supply in Great Britain, and a new experimental form was developed for use by the [[Royal Navy]].<ref name=ministry>Ministry of Munitions of War</ref> This was ''Cordite RDB'' (= ''R''esearch ''D''epartment formula ''B''); which was 52% [[collodion]], 42% [[nitroglycerin]] and 6% [[petroleum jelly]]. It was produced at [[HM Factory, Gretna]];<ref name=ministry/> and the [[Royal Navy Cordite Factory, Holton Heath]].{{Citation needed|date=January 2021}}

Acetone for the cordite industry during late World War I was eventually produced through the efforts of Dr. [[Chaim Weizmann]], considered to be the father of [[industrial fermentation]]. While a lecturer at [[Victoria University of Manchester|Manchester University]] Weizmann discovered how to use bacterial fermentation to produce large quantities of many desired substances. He used the bacterium ''[[Clostridium acetobutylicum]]'' (the so-called Weizmann organism) to produce acetone. Weizmann transferred the rights to the manufacture of acetone to the Commercial Solvents Corporation in exchange for royalties. After the [[Shell Crisis of 1915]] during World War I, he was director of the British Admiralty Laboratories from 1916 until 1919.{{Citation needed|date=January 2021}}

Cordite RDB was later found to become unstable if stored too long.{{Citation needed|date=January 2021}}

=== Cordite SC ===
Research on solvent-free Cordite RDB technologically extremely similar to ballistite continued primarily on the addition of stabilizers, which was based on German RP C/12 propellant featuring significant amounts of [[centralite]] (Called "carbamite" in British parlance) and led to the type commonly used in [[World War II]] as the main naval propellant. In Great Britain this was known as ''Cordite SC'' (= Solventless Cordite), and it required production facilities separate from classical cordite.

Cordite SC was produced in different shapes and sizes, so the particular [[geometry]] of Cordite SC was indicated by the use of letters or numbers, or both, after the SC. For example, SC followed by a number was rod-shaped cord, with the number representing the diameter in [[Thou (unit of length)|thou]]sandths of an inch. "SC T" followed by two sets of numbers indicated tubular propellant, with the numbers representing the two diameters in thousandths.{{Citation needed|date=January 2021}}

Two-inch (approximately 50&nbsp;mm) and three-inch (approximately 75&nbsp;mm) diameter, rocket Cordite SC charges were developed in great secrecy before World War II for anti-aircraft purposes—the so-called ''Z batteries'', using '[[Unrotated Projectile]]s'.<ref name=brown-chapter17/>

Great Britain changed to [[metric system|metric]] units in the 1960s, so there was a discontinuity in the propellant geometry numbering system.{{Citation needed|date=January 2021}}

=== Cordite N ===
An important development during World War II was the addition of another explosive, [[nitroguanidine]], to the mixture to form ''triple-base'' propellant or ''Cordite N'' and ''NQ''. The formulations were slightly different for artillery and naval use. This solved two problems associated with the large naval guns fitted to British Navy's [[capital ship]]s: gun flash and muzzle erosion.  Nitroguanidine produces large amounts of [[nitrogen]] when heated, which had the benefit of reducing the muzzle flash, and its lower burning temperature greatly reduced the erosion of the gun barrel.{{Citation needed|date=January 2021}}

N and NQ were also issued in limited amounts to ammunitions used by the British [[Ordnance QF 25-pounder|25-pdr]] and [[BL 5.5-inch Medium Gun|5.5-inch]] land-based artillery pieces.{{Citation needed|date=January 2021}}

After World War II production of double-base propellants generally ended. Triple-base propellants, N and NQ, were the only ones used in new ammunition designs, such as the cartridges for 105&nbsp;mm Field and for 155&nbsp;mm [[FH70]].{{Citation needed|date=January 2021}}