Puddling Furnace

A puddling furnace is a coal-fired reverberatory furnace used to convert brittle pig iron from a blast furnace into malleable wrought iron, keeping hot air over the iron without letting the fuel touch it directly while a worker stirs the metal through work doors with long hooked bars called rabbles. The ironmaster Peter Onions built the first successful commercial puddling furnace at Dowlais in 1783 and patented it, and the ironmaster Henry Cort improved the design at Fontley, Hampshire in 1783 and 1784, patenting an added chimney damper that prevented the iron from overheating. Puddling let Britain and, soon after, North America expand iron production dramatically without depending on charcoal, and the process remained a mainstay of iron manufacturing through much of the nineteenth century.