In the 18th century, black powder was generally made in specialized **powder mills**, not casually mixed by individual soldiers. It consisted of three materials: refined **saltpeter** (potassium nitrate), **charcoal**, and **sulfur**.
The industrial process broadly involved:
1. **Refining the ingredients:** Saltpeter was purified by dissolving, filtering, and recrystallizing it. Charcoal was produced from selected woods under limited air, while sulfur was cleaned and ground.
2. **Grinding separately:** Each ingredient was reduced to a fine consistency, usually in dedicated equipment to limit accidental ignition.
3. **Incorporating:** The materials were combined in water-powered wooden or stone mills. Moisture was added to reduce dust and sparks and to help form a uniform mass.
4. **Pressing:** The damp mixture was compressed into dense “mill cake,” improving consistency and performance.
5. **Corning:** The cake was broken into grains and passed through sieves. Different grain sizes were selected for muskets, cannon, pistols, or priming powder.
6. **Drying and finishing:** Grains were carefully dried, sometimes polished or “glazed” in rotating barrels, and then packaged in moisture-resistant containers.
Manufacture was extremely dangerous. Mills used lightweight buildings separated by distance, non-sparking tools, strict clothing rules, and blast walls; despite this, explosions were common. Powder quality varied substantially depending on saltpeter purity, charcoal quality, grain size, moisture, and how thoroughly the ingredients had been incorporated.