## The Basic Materials
Black powder required three ingredients, and in the 18th century acquiring them was often harder than combining them.
**Saltpeter (potassium nitrate)** was the critical and most expensive component, making up roughly three-quarters of the mixture. Britain had an enormous advantage here: the East India Company imported it from Bengal, where villagers extracted it from nitrate-rich soils around settlements and refined it in earthen pots. Continental powers lacking that supply relied on domestic "niter beds" or *nitrières* — walled heaps of manure, straw, ashes, and urine, periodically turned and watered, which after a couple of years were leached with water and the liquor boiled down to crystallize crude saltpeter. Several states, notably Prussia and France, imposed collection obligations on households and granted saltpeter-men rights to dig up stable floors and cellars, which was deeply unpopular.
**Sulfur** came largely from Sicilian volcanic deposits, distilled or sublimed to purify it.
**Charcoal** was made locally from soft, low-resin woods — willow, alder, buckthorn, dogwood — charred in kilns or, from the 1780s in Britain, in closed iron cylinders, a method associated with Richard Watson that produced more consistent charcoal and noticeably better powder.
## State Control and Organization
Powder-making was too militarily important to leave alone. Britain's Board of Ordnance bought the Faversham mills in 1759 and established Waltham Abbey in 1787, while also buying from private contractors in Surrey and Kent. France reorganized its industry in 1775 as the Régie royale des poudres et salpêtres, with Antoine Lavoisier as one of its commissioners; his systematic work on saltpeter refining and quality control substantially improved French powder — a contribution often credited with helping at Yorktown. Sweden, Spain, and Venice ran comparable monopolies.
## The Manufacturing Sequence
The refined ingredients were separately ground and sieved, then combined and subjected to **incorporation** — prolonged mechanical working with a small amount of added moisture, which is what actually creates powder rather than a mere mixture. Early in the century this was done in stamp mills, batteries of wooden pestles lifted by a water-driven camshaft; these were notoriously prone to setting off the charge. Over the middle decades they were largely replaced by edge-runner mills, in which heavy stone or iron wheels rotated in a circular bed — safer, faster, and giving a more thoroughly worked product.
The resulting mill cake was then **pressed** under screw or hydraulic pressure into dense slabs, **broken and corned** by passing it through sieves to produce graded grains (fine for muskets and pistols, coarse for cannon), **glazed** in rotating barrels — sometimes with graphite, a practice spreading late in the century — to round the grains and reduce dust absorption, then **dusted** and finally **dried**, either on canvas in the sun or in gently heated stove houses.
## Testing
Quality was judged by proof mortars, or *éprouvettes*, which fired a standard weight of shot with a measured charge; the range indicated strength. Cruder tests included burning a small quantity on paper to see whether it left residue or scorched the sheet.
## Danger and Site Design
Explosions were routine and often fatal. Mills were built as scattered arrangements of light buildings separated by earth mounds, trees, and watercourses, with weak walls and roofs designed to vent a blast upward. Workers wore leather or felt shoes without nails, used copper, bronze, and wooden tools, and floors were kept damp. Even so, catastrophic accidents destroyed mills at Faversham, Waltham Abbey, and elsewhere repeatedly across the century.
## The American Case
The colonies had almost no powder industry in 1775, having imported nearly all their supply. Congress published saltpeter instructions, offered bounties, and encouraged niter beds, and mills were established in Pennsylvania and elsewhere — but domestic production remained inadequate, and the great majority of powder used in the Revolution came from France and the Netherlands. Serious American manufacturing arrived only in 1802, when Éleuthère Irénée du Pont, trained in the French Régie under Lavoisier, built his works on the Brandywine.
If you're interested in a particular thread here — the saltpeter trade, Lavoisier's administrative reforms, or the archaeology of mill sites like Faversham — I can go further.