Richard Williams


This is the fourth and final paper on the importance of the type of iron which came from an 18th-century blast furnace. It deals with fining, turning the pig iron into malleable or wrought iron. Whether fining using charcoal or coal, the most important factor was whether the pig iron starting point was a high-silicon grey iron or a low-silicon white one. Both the chemical influence of silicon and the physical state that it induced was important. A grey iron contained graphite and melted to a proper liquid which was much more difficult to oxidise than the pasty mix that a white iron produced. Carbon in the form of graphite (in grey iron) was much slower to diffuse than when it was in the form of iron carbide (in white iron). These key differences influenced the fining processes in the early charcoal finery hearths, and in the potting and stamping processes, as much as they did in puddling.


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How to Cite
Grey or white pig? The importance of the starting material whether fining iron in charcoal hearths, clay pots or puddling furnaces. (2022). Historical Metallurgy, 53(2), 84-103.