To create gunpowder in Windrose, you need 10 units of sulfur and 20 units of ash, which must be combined at a Millstone. You cannot craft gunpowder until you complete the main quest "Revenge is Best Served Cold." Sulfur can only be mined with an Iron Pickaxe, which requires significant game progression. Before crafting gunpowder, you must complete the quests "Rescuing the Crew" and "I Need a Bigger Boat," defeat Thomas Richards, travel to the Foothills to mine Foothills Iron Ore for ingots, discover corn in the Foothills to unlock the Millstone recipe, and craft an Iron Pickaxe. Sulfur can be found in the Coastal Jungle and Foothills biomes, while ash can be obtained from burning wood at the Charcoal Kiln or grinding charcoal at the Millstone.