Elterwater and Low-wood are two sites in Lakeland that show clear remains of the once thriving black powder or gunpowder industry. Michael Davies Shiel is the recognized authority on the subject. The growing demand for the powder came from quarrying and mining across the North. Saltpetre and sulphur were imported as vital ingredients. The other requirement was charcoal, something obtainable from the coppicing of the areas woodland. Water power was equally important with the earliest works being on the River Kent, south of Kendal.
The Elterwater works on the River Brathay, now a holiday complex, (Langdale Estates)are still traceable on the ground. The areas last gunpowder mills closed in 1937. Saltpetre came from Chile and barrels used to arrive at Windermere railway station for onward transport. Sulphur came from volcanic regions such as Stroboli on Sicily. Coppice wood was fed into the greedy retort furnaces to produce quality charcoal at Gatebeck. Careful grinding and mixing are the requirements for black powder manufacture. Thus a series of small water driven grinders and mixers would be spread along a watercourse such as the Brathay. The risks of explosions in the process means that work was spread between blast banks in an attempt to limit the potential for disaster. Any furnaces for drying also had long covered flues to carry away the sparks well away from the gunpowder areas. Rotary churns and heavy iron or stone runners were all designed to crush and mix the ingredients. But always they had to be designed to prevent that stray spark that could end with an explosion.
In the latter stages of the industry large waterwheels were replaced by the turbines that became the hallmark of Kendal firm Gilbert Gilkes and Gordon. Elterwater boasted six water wheels. The friction generated in some of the earlier grinding processes led to fatal explosions. The crude black powder was then compressed under great pressure into sheets before the dangerous process of corning into identical sized pieces for even explosion. Early corning was done by mallet Equally hair raising was the later stage of drying the mixture before careful packaging. The site at Sedgewick is completely overgrown today. Black powder from these Lakeland works was used around the world, but also nearer home for the iron ore mining of West Cumbria and Furness.