Henry Cort and the Puddling Revolution in Iron

Cast iron is strong but brittle; wrought iron is tougher and could be hammered and shaped, which made it more useful for tools, chains and machine parts. Making wrought iron had been slow and relied on charcoal. In 1783 and 1784 Henry Cort patented two linked processes: puddling, in which molten pig iron was stirred in a coal-fired furnace to burn off carbon, and rolling the hot iron through grooved rollers instead of hammering it.

These methods let ironmakers produce wrought iron in large quantities using coal. British iron output soared, from about 68,000 tons of pig iron in 1788 to more than 2 million tons by around 1850. Puddling was brutal work, demanding great strength in intense heat. Cort himself was ruined when it emerged that his business had been financed with navy funds embezzled by his partner's father, a naval official, and he gained little from his inventions.