The earliest bloomeries – from the Iron Age to the Middle Ages – had bellows worked by foot (or hand), even though many were sited by water which was used for other purposes such as washing the ore or puddling the clay for lining the hearth.īloomeries were widespread, temporary and seasonal in operation. This was wrought iron, which can be shaped by hammering, squeezing or rolling, but not melted and poured into a mould like cast iron. It was then transferred to the smelting hearth where it was reheated and hammered into the required shape. Once the process was judged to be complete, the iron was taken out using long-handled tongs, and hammered on an anvil to expel surplus slag and to consolidate and weld together the iron into a bloom. The iron gathered within the base of the tower, above the tuyeres through which the air was pumped. The temperature inside the hearth was crucial – high enough to melt the ore, but not too high as above a certain temperature the iron took up carbon and became cast iron which at that time was brittle and useless. When iron ore is heated in contact with carbon (the charcoal), the oxygen in the ore unites with the carbon to form an inflammable gas – carbon monoxide – which burns away, leaving a spongy mass of semi-molten iron behind. By the Middle Ages the bloomeries were taller and larger, producing 5-10kg blooms. A typical charge of 15kg of ore (and the same of charcoal) would give a 1.5 kg bloom – the size of a man’s fist – sufficient for just one or two finished products such as farm tools. A fresh charge, in equal weights of ore and charcoal, would be added regularly until it was judged that there was enough for the size of the hearth. Once the temperature was sufficiently high – somewhere between 950✬ and 1125☌ – a charge of small pieces of ore and more charcoal would be added through the open top of the furnace. Charcoal in the furnace was set alight using chopwood, bellows used to pump air into the fuel to raise the temperature, and more charcoal added to keep the furnace full. Bloomery sites were mostly located within the woodlands from which the charcoal was produced – rather than at the orefields – because vast amounts of it were used in the smelting process and the light and brittle charcoal did not travel well.Ī bloomery furnace took a number of forms, but in Lakeland typically had a base made of clay and stone, upon which was constructed a waist high tower made of clay on a coppice oak framework, with an internal diameter of 30-40cms at the base. The earliest method of producing iron was by smelting iron ore in a small furnace or hearth known as a bloomery, using charcoal as the fuel. Please contact me at if you know of any other information I can add, or recognise any errors. The sources of information I have used are listed after each section and at the end. It concentrates on production rather than use – the many foundries and engineering works in the county deserve a chapter of their own. So this is very much an introduction to what was a major industry in Cumbria, with links and suggestions for anyone wanting to discover more. ![]() The manufacture of iron and steel is a big subject, not easy to condense into a few pages. Listed Bridges in the Lake District National Parkīlast furnaces – charcoal fired Blast furnaces – coke fired.The Rowrah and Kelton Fell (Mineral) Railway.The charcoal/coke blast furnaces of Cumbria.The Land Settlement Association in Cumbria.Know your mill buildings – an expert’s guide. ![]() Buyer’s Guide to Cumberland and Westmorland.Barrow 1901 – a description of its industries.
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