The sword is a weapon full of imagery – of great armies and knights – but it also parallels the metallurgical developments that made its use possible.
Its invention, the date of which is still disputed, grew from the lengthening of daggers. These shorter weapons were originally made from copper, which although readily available is a relatively soft metal unsuited to anything other than a short stabbing weapon.
The creation of the longer, sharp-edged, swinging and cutting weapon could not occur without the development of a harder metal. For that reason, its first appearance is thought to be between the 17th – 16th century BC in the Black Sea region. This period would later become known as the Bronze Age.
By adding tin to the copper, a harder alloy (bronze) could be created, which advanced the development of the sword; even though ancient swordsmiths may not have understood all the alloy’s properties, there is evidence that they were able to vary the composition to create different effects depending on their battle priorities. For example, early Chinese swordsmiths preferred to use a higher percentage of tin (circa 20%) to create a harder, though more brittle, sword, whereas other regions used a lower percentage of tin (circa 10%) for a sword less likely to break in battle, although more likely to bend.
It was not until the Iron Age (12th – 13th century BC), however, that longer, sturdier swords could be developed.
By smelting raw iron (iron ore) using extreme heat and coal to bind the oxygen in the iron ore, swordsmiths were able to produce swords of almost pure iron with carbon dioxide as a by-product.
Smelting was first made possible through the use of bloomeries, now superseded by the blast furnace. At the time, iron’s high melting point meant that swordsmiths could only produce a porous iron mass called a bloom, which then had to be hammered out over several cycles of heating and cooling in order to produce a sword. It must be said, however, that these iron swords were only slightly better in terms of strength and hardness than the bronze swords before them, but iron was very widely available, and the process was far simpler than that of producing a bronze sword, allowing for larger scale production and bigger, sword-carrying armies, with predictable consequences.
Over time, swordsmiths discovered that by adding charcoal (carbon) during the iron smelting process, and by quenching to increase hardness, then tempering to take away the brittleness, they could make far harder and resilient swords which did not lose their shape. The process was, however, not easy to control and it took centuries before the smiths learned to create the new alloy – steel – in any consistent way. The result was swords of vastly varying quality; indeed into the early Middle Ages, some swords were still being made from iron. It was centuries before the true properties of steel were understood.
Video: ‘Liquid Fire’ to Metal Sword in minutes, A History of Ancient Britain—Ep4, BBC2 https://www.youtube.com/watch?v=eEWIuyeNp2k
Sources: Gonzalez, R A brief history of the ancient science of sword making http://io9.gizmodo.com/5831683/a-brief-history-of-the-ancient-science-of-sword-making
The Japanese Samurai Sword
It is said that the Japanese master swordsmith, Masamune, accidentally knocked some powder he’d been using as an asthma medication into the molten metal he was preparing for one of his swords. Despite considering abandoning the melt, he decided to continue and finish the blade. What he did not know was that the grey powder was molybdenum, and the Katana Samurai blade that resulted was not only harder and sharper than anything that had been seen before, but also far more flexible. It was said to be able to slice through a human body from collar bone to hip in a single stroke.
Masamune’s accident led to a revolution in steelmaking and to Japan’s dominance of the global weapons’ industry, a status they did not relinquish until the introduction of flintlock muskets almost 300 years later.
Japanese swordsmithing is a traditional smelting process using several layered steels with different carbon concentrations to strengthen the blade and cause the blade to curve due to the different densities of the layers of steel within it.
The blade is then polished for up to three weeks leaving the hamon – the distinct line down the sides of the blade – with a matte finish along the blunt edge.
Image Author: By loulasedna – loulasedna, CC BY-SA 3.0,
Video: Samurai Swordmaking, Portland Art Museum https://www.youtube.com/watch?v=2WkWNDDrQO4
Sources: Energy & Capital http://www.energyandcapital.com/articles/investing-in-molybdenum/1136
Maria Cox, MMTA