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For other meanings, see gunpowder (disambiguation).

Gunpowder, also called black powder, is a mixture of sulfur, charcoal, and potassium nitrate. It burns rapidly, producing a volume of hot gas and a solid residue which can be used as a propellant in firearms and as a pyrotechnic composition in fireworks. The term gunpowder also refers broadly to any propellant powder. Modern firearms do not use the traditional gunpowder (black powder) described in this article, but instead use smokeless powder. Antique firearms or replicas of antique firearms are often used with black powder substitute.

Gunpowder is classified as a low explosive because of its relatively slow decomposition rate and consequently low brisance. Low explosives deflagrate at subsonic speeds. High explosives detonate, producing a supersonic wave. The gases produced by burning gunpowder generate enough pressure to propel a bullet, but not enough to destroy a gun barrel. This makes gunpowder less suitable for shattering rock or fortifications, where high explosives such as TNT are preferred.

Characteristics

The term black powder was coined in the late 19th century to distinguish prior gunpowder formulations from the new smokeless powders and semi-smokeless powders.(Semi-smokeless powders featured bulk volume properties that approximated black powder in terms of chamber pressure when used in firearms, but had significantly reduced amounts of smoke and combustion products; they ranged in color from brownish tan to yellow to white. Most of the bulk semi-smokeless powders ceased to be manufactured in the 1920s.)

Black powder is a granular mixture of

• a nitrate, typically potassium nitrate (KNO₃), which supplies oxygen for the reaction;
• charcoal, which provides carbon and other fuel for the reaction, simplified as carbon (C);
• sulfur (S), which, while also a fuel, lowers the temperature of ignition and increases the speed of combustion.

Potassium nitrate is the most important ingredient in terms of both bulk and function because the combustion process releases oxygen from the potassium nitrate, promoting the rapid burning of the other ingredients. To reduce the likelihood of accidental ignition by static electricity, the granules of modern black powder are typically coated with graphite, which prevents the build-up of electrostatic charge.

The current standard composition for the black powders that are manufactured by pyrotechnicians was adopted as long ago as 1780. Proportions by weight are 75% potassium nitrate, 15% softwood charcoal, and 10% sulfur. These ratios have varied over the centuries and by country, and can be altered somewhat depending on the purpose of the powder. For instance, power grades of black powder, unsuitable for use in firearms but adequate for blasting rock in quarrying operations, is called blasting powder rather than gunpowder with standard proportions of 70% nitrate, 14% charcoal, and 16% sulfur; blasting powder may be made with the cheaper sodium nitrate substituted for potassium nitrate and proportions may be as low as 40% nitrate, 30% charcoal, and 30% sulfur.

Combustion rate

The burn rate of black powder can be changed by corning. Corning first compresses the fine black powder meal into blocks with a fixed density (1.7 g/cm³). The blocks are then broken up into granules. These granules are then sorted by size to give the various grades of black powder. In the United States, standard grades of black powder run from the coarse Fg grade used in large bore rifles and small cannons, through FFg (medium and smallbore arms such as muskets and fusils), FFFg (smallbore rifles and pistols), and FFFFg (extreme small bore, short pistols and most commonly for priming flintlocks). In the United Kingdom, the gunpowder grains are categorised by mesh size: the BSS sieve mesh size, being the smallest mesh size on which no grains were retained. Recognised grain sizes are Gunpowder G 7, G 20, G 40, and G 90.

A simple, commonly cited, chemical equation for the combustion of black powder is

2 KNO₃ + S + 3 C → K₂S + N₂ + 3 CO₂.

A more accurate, but still simplified, equation is

10 KNO₃ + 3 S + 8 C → 2 K₂CO₃ + 3 K₂SO₄ + 6 CO₂ + 5 N₂.

Another reaction may be:

6 KNO₃ + C₇H₄O + 2 S → 2 K₂S + 4 CO₂ + 3 CO + 2 H₂O + 2 N₂

Charcoal does not consist of pure carbon; rather, it consists of partially pyrolyzed cellulose, in which the wood is not completely decomposed.

The burning of gunpowder does not take place as a single reaction, however, and the byproducts are not easily predicted. One study's results showed that it produced (in order of descending quantities): 55.91% solid products: potassium carbonate, potassium sulfate, potassium sulfide, sulfur, potassium nitrate, potassium thiocyanate, carbon, ammonium carbonate. 42.98% gaseous products: carbon dioxide, nitrogen, carbon monoxide, hydrogen sulfide, hydrogen, methane, 1.11% water.

Black powder formulations where the nitrate used is sodium nitrate tend to be hygroscopic, unlike black powders where the nitrate used is saltpeter (saltpeter (also saltpetre) in the context of this article means specifically potassium nitrate and not other definitions). Because of this, black powder which uses saltpeter can be stored unsealed and remain viable for centuries provided no liquid water is ever introduced. Muzzleloaders have been known to fire after hanging on a wall for decades in a loaded state, provided they remained dry. By contrast, powder that uses sodium nitrate, which is typically intended for blasting, must be sealed from moisture in the air to remain stable for long times.

Advantages

In firearms, black powder allows loading by volumetric measure, where as smokeless powder requires precise measuring of the charge by weight to prevent damage due to overloading, though damage by overloading is still possible with black powder.

In quarrying, high explosives are generally preferred for shattering rock. However, because of its low brisance, black powder causes fewer fractures and results in more usable stone compared to other explosives, making black powder useful for blasting monumental stone such as granite and marble.

Black powder is well suited for blank rounds, signal flares, burst charges, and rescue-line launches. Black powder is also used in fireworks for lifting shells, in rockets as fuel, and in certain special effects.

Disadvantages

Black powder has low energy density compared to modern smokeless powders and produces a thick smoke that can impair aiming and reveal a shooter's position.

Combustion converts less than half the mass of black powder to gas. The rest ends up as a thick layer of soot inside the barrel. In addition to being a nuisance, the residue from burnt black powder is hygroscopic and an anhydrous caustic substance. When moisture from the air is absorbed, the potassium oxide or sodium oxide turns into hydroxide, which will corrode wrought iron or steel gun barrels. Black powder arms must be well cleaned both inside and out to remove the residue. The Matchlock musket (an early gun) would be unusable in wet weather due to powder in the pan being exposed and dampened, in which case soldiers would use the ends as clubs or use bayonets.

Transportation

The UN Model Regulations on the Transportation of Dangerous Goods and national transportation authorities, such as United States Department of Transportation, have classified Gunpowder (black powder) as a Group A: Primary explosive substance for shipment because it ignites so easily. Complete manufactured devices containing black powder are usually classified as Group D: Secondary detonating substance, or black powder, or article containing secondary detonating substance, such as firework, class D model rocket engine, etc., for shipment because they are harder to ignite than loose powder. As explosives, they all fall into the category of Class 1.

Energy content

Gunpowder contains 3 megajoules per kilogram, and contains its own oxidant. For comparison, the energy density of TNT is 4.6 megajoules per kilogram, and the energy density of gasoline is 47.2 megajoules per kilogram.

Sulfur-free gunpowder

The development of smokeless powders, such as Cordite, in the late 19th century created the need for a spark-sensitive priming charge, such as gunpowder. However, the sulfur content of traditional gunpowders caused corrosion problems with Cordite Mk I and this led to the introduction of a range of sulfur-free gunpowders, of varying grain sizes. They typically contain 70.5 parts of saltpetre and 29.5 parts of charcoal. Like black powder, they were produced in different grain sizes. In United Kingdom, the finest grain was known as sulfur-free mealed powder (SMP). Coarser grains were numbered as sulfur-free gunpowder (SFG n): 'SFG 12', 'SFG 20', 'SFG 40' and 'SFG 90', for example, where the number was a BSS sieve mesh size, being the smallest mesh size on which no grains were retained.

The main purpose of sulfur in gunpowder is to decrease the ignition temperature. A sample reaction for sulfur-free gunpowder would be:

4 KNO₃ + C₇H₈O → 3 K₂CO₃ + 4 CO₂ + 2 H₂O + 3 N₂

BOOM

Manufacturing technology

For the most powerful black powder meal, a wood charcoal is used. The best wood for the purpose is Pacific willow, but others such as alder or buckthorn can be used. The ingredients are mixed as thoroughly as possible. This is achieved using a ball mill with non-sparking grinding apparatus (e.g., bronze or lead), or similar device. Historically, a marble or limestone edge runner mill, running on a limestone bed was used in Great Britain; however, by the mid 19th century AD this had changed to either an iron shod stone wheel or a cast iron wheel running on an iron bed. The mix is sometimes dampened with alcohol or water during grinding to prevent accidental ignition.

Around the late 14th century AD, European powdermakers began adding damp to the constituents of gunpowder to reduce dust and with it the risk of explosion. The powdermakers would then shape the resulting paste of dampened gunpowder, known as mill cake, into corns, or grains, to dry. Not only did corned powder keep better because of its reduced surface area, gunners also found that it was more powerful and easier to load into guns. Before long, powdermakers standardized the process by forcing mill cake through sieves instead of corning powder by hand.

During the 18th century gunpowder factories became increasingly dependent on mechanical energy.

Other uses

Besides its habitual use as an explosive, gunpowder has been occasionally employed for other purposes, After the battle of Aspern-Essling (1809), the surgeon of the Napoleonic Army Larrey combated the lack of food for the wounded under his care by preparing a bouillon of horse meat seasoned with gunpowder for lack of salt. It was also used for sterilizing on ships when there was no alcohol.

Christiaan Huygens experimented with gunpowder in 1673 in an early attempt to build an internal combustion engine. He did not succeed in making a practical engine.

Fireworks and Firecrackers also use gunpowder but use different brands and different chemicals.

See also

• Ballistics
• Ballincollig Royal Gunpowder Mills
• Cannon
• Faversham explosives industry
• Gunpowder magazine
• Gunpowder Plot
• Gunpowder warfare
• History of gunpowder
• Smokeless powder
• Technology of the Song Dynasty
• Waltham Abbey Royal Gunpowder Mills

Notes

1. The History of the 10.4×38 Swiss Cartridge
2. Blackpowder to Pyrodex and Beyond by Randy Wakeman at Chuck Hawks
3. The History and Art of Shotshells by Jon Farrar, Nebraskaland Magazine
4. Buchanan. "Editor's Introduction: Setting the Context", in Buchanan 2006, p. 4.
5. ^ Earl 1978, Chapter 2: The Development of Gunpowder
6. Julian S. Hatcher, Hatcher's Notebook, Military Service Publishing Company, 1947. Chapter XIII Notes on Gunpowder, pages 300-305.
7. Flash! Bang! Whiz!, University of Denver
8. workshop first week
9. ^ Cocroft 2000, "The demise of gunpowder". Chapter 4
10. U.S. Department of Agriculture (1917). Department Bulleting No. 316: Willows: Their growth, use, and importance. p. 31.
11. Kelly 2004:60–63
12. Frangsmyr, Tore, J. L. Heilbron, and Robin E. Rider, editors The Quantifying Spirit in the Eighteenth Century. Berkeley: University of California Press, c1990. http://ark.cdlib.org/ark:/13030/ft6d5nb455/ p. 292.
13. Harold T Parker. (1983 reprint) Three Napoleonic Battles. (2nd Ed). Duke University Press. ISBN 0-82230547-X. Page 83 (in Google Books). Quoting Dominique-Jean Larrey, Mémoires de chirurgie militaire et campagnes, III 281, Paris, Smith.
14. Larrey is quoted in French at Dr Béraud, Études Hygiéniques de la chair de cheval comme aliment, Musée des Familles (1841-42).

References

• Brown, G. I. (1998), The Big Bang: A History of Explosives, Sutton Publishing, ISBN 0-7509-1878-0.
• Buchanan, Brenda J., ed. (2006), Gunpowder, Explosives and the State: A Technological History, Aldershot: Ashgate, ISBN 0754652599.
• Chase, Kenneth (2003), Firearms: A Global History to 1700, Cambridge University Press, ISBN 0521822742.
• Cocroft, Wayne (2000), Dangerous Energy: The archaeology of gunpowder and military explosives manufacture, Swindon: English Heritage, ISBN 1-85074-718-0.
• Crosby, Alfred W. (2002), Throwing Fire: Projectile Technology Through History, Cambridge University Press, ISBN 0521791588.
• Earl, Brian (1978), Cornish Explosives, Cornwall: The Trevithick Society, ISBN 0-904040-13-5.
• al-Hassan, Ahmad Y., "Gunpowder Composition for Rockets and Cannon in Arabic Military Treatises In Thirteenth and Fourteenth Centuries", History of Science and Technology in Islam.
• Johnson, Norman Gardner, "explosive", Encyclopædia Britannica, Chicago: Encyclopædia Britannica Online.
• Kelly, Jack (2004), Gunpowder: Alchemy, Bombards, & Pyrotechnics: The History of the Explosive that Changed the World, Basic Books, ISBN 0465037186.
• Khan, Iqtidar Alam (1996), "Coming of Gunpowder to the Islamic World and North India: Spotlight on the Role of the Mongols", Journal of Asian History, 30: 41–5.
• Khan, Iqtidar Alam (1996a). "The Role of the Mongols in the Introduction of Gunpowder and Firearms in South Asia". Chapter 3, In Buchanan, Brenda J. (1996). Gunpowder: The History of an International Technology. Bath: Bath University Press. (ISBN 0-86197-134-5. 2006 re-issue).
• Khan, Iqtidar Alam (2004), Gunpowder and Firearms: Warfare in Medieval India, Oxford University Press.
• Needham, Joseph (1986), Science & Civilisation in China, vol. V:7: The Gunpowder Epic, Cambridge University Press, ISBN 0521303583.
• Norris, John (2003), Early Gunpowder Artillery: 1300-1600, Marlborough: The Crowood Press.
• Partington, J.R. (1960), A History of Greek Fire and Gunpowder, Cambridge, UK: W. Heffer & Sons.
• Partington, James Riddick (1999). A History of Greek Fire and Gunpowder. Baltimore: Johns Hopkins University Press. ISBN 0-8018-5954-9. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
• Urbanski, Tadeusz (1967), Chemistry and Technology of Explosives, vol. III, New York: Pergamon Press.

External links

• Gun and Gunpowder
• The Origins of Gunpowder
• Cannons and Gunpowder
• Oare Gunpowder Works, Kent, UK
• Royal Gunpowder Mills
• The DuPont Company on the Brandywine A digital exhibit produced by the Hagley Library that covers the founding and early history of the DuPont Company powder yards in Delaware
• "Ulrich Bretschler's Gunpowder Chemistry page".

• Explosives
• Pyrotechnic compositions
• Firearm propellants
• Granular materials
• Traditional Chinese objects