Black powder is a type of gunpowder invented in the 9th Century and practically the only propellant and explosive known until the middle of the 19th Century. It was used as an explosive and a propellant in firearms until the early 20th Century. It was superseded by other substances such as smokeless powders and dynamite due to its combustion products being 60% solid particulates, and thus its tendency to foul gun barrels.

Black powder is quite good propellant, but rather poor for an explosive. However, it was the only explosive available for mining for several centuries. It is still manufactured today, but primarily for use in fireworks, model rocket engines, and reproduction weapons.

Black powder consists of the granular ingredients sulfur (S), charcoal (provides carbon to the reaction) and saltpeter (saltpetre, potassium nitrate, KNO₃; provides oxygen to the reaction).

The optimum proportions for gunpowder are: saltpetre 74.64%, sulfur 11.85%, charcoal 13.51% (by weight not volume). A more basic ratio is: 2 parts sulfur, 3 parts charcoal, 15 parts saltpetre. The current standard for black powder manufactured by pyrotechnicians today is 75% potassium nitrate, 15% softwood charcoal and 10% sulfur.

For the most powerful black powder "meal" a wood charcoal is used. The best wood for the purpose is buckthorn, but others such as balsa or willow can be used. The ingredients are mixed as thoroughly as possible. This is achieved using a ball mill with non-sparking grinding apparatus (lead), or similar device.

Black powder is also corned to change its burn rate. Corning is a process which 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. Standard grades of black powder run from the coarse Fg grade used in large bore rifles and small cannon though FFg (medium and smallbore rifles), FFFg (pistols), and FFFFg (smallbore, short pistols and priming flintlocks). Very coarse black powder was used in mining before the development of nitroglycerine and dynamite.

Although black powder is not a true high explosive, the United States Department of Transportation classifies it as a "Class A High Explosive" for shipment because it is so easily ignited. Highly destructive explosions at fireworks manufacturing plants are rather common events, especially in Asia. Complete manufactured devices containing black powder are usually classified as "Class C Firework", "Class C Model Rocket Engine", etc. for shipment because they are harder to ignite than the loose powder.

Gunpowder was invented in China in the 9th century during the Tang dynasty. The invention appears to have been by accident by alchemists seeking the elixir of immortality, or possibly as a fire starter for the easy ignition of tinder by sparks. The first references to gunpowder appear as warnings in alchemy texts not to mix certain materials together. By the 10th century, gunpowder began to be used for military purposes in China in the form of rockets and explosive bombs fired from catapults. The first reference to cannon appears in 1126 when oil bamboo tubes were used to launch missiles at the enemy. Eventually bamboo tubes were replaced by metal tubes, and the oldest cannon in China dates from 1290. From China, the military use of gunpowder appears to have spread to Japan and Europe. It was used by the Mongols against the Hungarians in 1241 and was mentioned by Roger Bacon in 1248. By the mid 14th century, early cannons are mentioned extensively both in Europe and in China.

In China as in Europe, the use of gunpowder to produce firearms and cannon was delayed by difficulties in creating metal tubes that would contain an explosion. This problem may have led to the false myth that the Chinese used their invention only for the manufacture of fireworks. In fact, gunpowder powered cannon and rockets were extensively used in the Mongol conquests of the 13th century and were a feature of East Asian warfare afterwards. The short squat and thick city walls of Beijing for example, were specifically designed to withstand an artillery attack, and the Ming dynasty moved the capital from Nanjing to Beijing specifically because the hills around Nanjing were good locations for invaders to place artillery.

The 15th through 17th century saw widespread development in gunpowder technology both in Europe and the Far East. Advancements in metallurgy led to small weapons and the development of muskets. Cannon technology in Europe gradually outpaced that of China and these technological improvements transferred back to China through Jesuit missionaries who were put in charge of cannon manufacture by the late Ming and early Qing emperors.

The latter half of the 19th Century saw the invention of nitroglycerin, nitrocellulose and smokeless powders which rapidly led to the replacement of gunpowder in many applications.

• Meal powder
• Green mix
• Smokeless powder

• Gunpowder: Alchemy, Bombards, & Pyrotechnics by Jack Kelly, Basic Books, ISBN 0-465-03718-6.