Casting history: fun facts
While researching our recent articles on the history of casting, we uncovered some interesting facts we just had to share!
A heavy metal burial
John Wilkinson, the creator of the cupola furnace, had such a passion for iron work that when he died in 1808, he was buried in an iron coffin beneath an iron obelisk in Cumbria, England. And we thought we were passionate about iron. It looks like we’ve met our match!
When was it really invented?
In part two of the history of iron casting article, we also discussed how the crucible process was invented by clockmaker Benjamin Huntsman in the 1740s. Well, Huntsman only rediscovered what was invented somewhere between 800 and 400 BCE.
To refresh your memory, the crucible process is a technique for producing steel by heating wrought iron with carbon-rich charcoal in closed vessels. It is said that, in about 800 BCE, the crucible process was used in Europe to make high-quality Ulfbehrt swords for Vikings!
However, some historians still believe that the crucible process was not invented until 500 or 400 BCE in India. As we’ve seen before, the early history of iron casting is shrouded in mystery.
What’s the buzz about beehive furnaces?
Another type of furnace used to smelt iron was called a beehive furnace. It was a dome-like structure, constructed by piling alternate layers of charcoal and iron ore. It was then covered with a thick layer of clay. Blowpipes connected to bellows were inserted through the lower side walls for heat and airflow. The bottom layer of charcoal was ignited and pressurized air was provided by the bellows. After each batch of iron was produced, the clay dome collapsed, and workers would dig out the iron from the demolished furnace, so the iron could be hammered to eliminate impurities.
Before this process could begin again, the furnace needed to be rebuilt. As you can probably imagine, this process was inefficient, time-consuming, took a lot of hard labor, and the product it yielded in one batch was small.
Beehive ovens were also used to turn coal into coke, a product important in iron making. Coal was burned to create coke, which was then used to fuel blast furnaces. Coke burned hotter than uncooked coal and therefore provided better fires for iron making. In the 1830s, beehive ovens began to be used extensively in the iron industry. By 1916, there were more than 46,000 of them being used for industrial purposes in the United States.
Iron makers are like gods
Mircea Eliade was a Romanian historian, philosopher and writer who published a book entitled The Forge and the Crucible. In his book, he details how in Chinese mythology, metallurgists in China’s Iron Age held secret knowledge and prodigious and formidable powers that made them the founders of the human world and masters of the spirit world. According to Eliade and Chinese mythology, there was a close relationship between mystical powers and the mining and metal-making industries of the Chinese world.
In a book entitled The Book of Immortals, Huangdi, a man known as the Yellow Emperor, gathered copper from Mount Shou and melted it at the foot of Mount Jing. As soon as the copper was melted, a bearded dragon came down and lifted the emperor up into the sky. It is believed that because of this, Huangdi was seen as a god in the tradition of this region.
The book also discusses how the Yellow Emperor fought Chiyou, the leader of the Sanmiao or Jiuli aborigines. This was a clan of blacksmiths known as the Seventy-two Brothers of Chiyou. Their heads were made of copper and iron, and they ate iron and stone. Chiyou was Huangdi’s rival. Before their fight, he had already defeated Xuanyuan, the future Yellow Emperor. The advancement of weaponry is sometimes attributed to the Yellow Emperor as well as to Chiyou. It was the latter who discovered the process of metal casting.
Britannica, The Editors of Encyclopaedia. “Crucible Process.” Encyclopædia Britannica. April 27, 2017. Accessed April 11, 2019. https://www.britannica.com/technology/crucible-process.
“Evolution of Blast Furnace Iron Making.” Ispatguru.com. Accessed April 11, 2019. http://ispatguru.com/evolution-of-blast-furnace-iron-making/.
Hirst, K. Kris. “Wootz Steel: 2,400 Years of Making Steel in a Crucible.” ThoughtCo. February 24, 2018. Accessed April 12, 2019. https://www.thoughtco.com/wootz-steel-raw-material-damascus-blades-173235.
“History of Metallurgy in China.” Wikipedia. April 04, 2019. Accessed April 12, 2019. https://en.wikipedia.org/wiki/History_of_metallurgy_in_China.
Study.com. Accessed April 11, 2019. https://study.com/academy/lesson/what-is-a-beehive-oven-history-method.html.
Wrexham County Borough Council, and Wrexham. “John Wilkinson – His Impact and Legacy.” John Wilkinson & Bersham Ironworks – John Wilkinson – His Impact and Legacy – WCBC. Accessed April 11, 2019. http://www.wrexham.gov.uk/english/heritage/bersham_ironworks/impact_legacy.htm.