“The discovery of King Tutankhamen’s tomb was one of the greatest archeological finds of all time. The lavish riches that were buried with the young king included more gold than the Royal Bank of Egypt had on deposit when the discovery was made in 1922. Among the 107 objects discovered on Tutankhamen’s body was an ornately decorated iron dagger that he carried on his belt. Presumably fashioned from meteoritic iron – very rare and much harder and tougher than the other metals available at the time – his dagger was considered so precious that the king would certainly want it with him in the afterlife. In an age dominated by the smelting of copper and its stronger alloy, bronze, iron was immeasurably valuable – more so than gold.
While iron oxide makes up over 6% of the Earth’s crust, it took a long time for mankind to figure out how to convert dirt into something as useful as steel. The first smelting of iron from ore was probably accidental when some iron-bearing ore was mixed in with the copper ore during the smelting of copper. Iron ore is composed mostly of various iron oxides which need to be reduced – have oxygen removed – to form metallic iron. The iron ore was mixed with charcoal, which is mostly carbon, and fired. The carbon dioxide produced by burning charcoal combines with the hot carbon in the charcoal, forming carbon monoxide. The hot carbon monoxide turns again to carbon dioxide by stealing oxygen from – reducing – the iron oxides leaving metallic iron behind. But the heat needed for melting copper isn’t nearly sufficient to melt the iron that may be present in the copper ore so the reaction from ore to iron occurs in a solid state and the iron forms into a solid, ugly mass of spongy metal called a bloom. The bloom’s cavities would be full of slag — molten impurities from the smelting that need to be removed. Someone must have recognized the spongy mass as a metallic substance probably by using appropriate scientific methodology such as hitting it with a rock. Eventually the bloom was processed by heating it to the slag’s melting point and hammering on it until all of the slag had squirted out. Hard, dangerous and resource-intensive work as the iron was reheated and beaten over and over to produce wrought iron. This process was the way iron was made from late BC to early AD.
Sometimes the bloom production could be managed so that it contained some carbon, and it is believed that the first steel was produced in East Africa as early as 1400 BC. The Chinese melted wrought iron and cast iron together to make a middle-carbon steel in the first century AD. Wootz steel, also known as Damascus or pattern welded steel – a layering of steels with different carbon contents – was being produced in India and Sri Lanka and was imported into China by the 5th century AD. The Celts made steel from bars of wrought iron in about 200 AD by enclosing them in an iron container with bones or other carbonaceous materials and heating the whole thing over high heat for ten to twelve hours. The iron absorbs the carbon and becomes steel that can then be forge-welded and shaped to produce tools.
Modern steel production took a huge leap forward in 1855 when Charles Bessemer patented a process that could remove impurities from iron by blowing air though the crucible of liquid metal. 15 tons or more of molten iron could be purified in 20 minutes by the Bessemer process, after which carbon and other alloying elements would be added in the desired proportions. Thus began the age of inexpensive, mass produced steel.”
Excerpt from pages 14 – 15 of The Perfect Edge, The Ultimate Guide to Sharpening for Woodworkers. We’ll include a $10 “Blade Bucks” certificate, good on a subsequent purchase, when you order The Perfect Edge from www.hocktools.com.