Fans of the literary saga A Song of Ice and Fire (or its television adaptation, Game of Thrones) will remember that “Valyrian steel” was a special alloy used to make bladed weapons in the now-lost city of Valyria, giving them unique quality and hardness; with the secret of its composition lost, these weapons became invaluable. As is often the case, this concept is based on historical reality: Damascus steel, which was used from the Middle Ages onward to manufacture near-eternal swords that were highly prized. But this Damascus alloy had its roots in an even older one that reached the Middle East from southern India: wootz steel.

Damascus steel was a crucible steel (made by heating and cooling metal in a crucible with charcoal), a technique that began in the 10th century and lasted until the mid-18th century. As its name suggests, tradition places its origin in the Syrian city of the same name, though it is possible that the term actually derives from the Arabic word damasqui. There are also certain references in Balkan legends that point to northern Macedonia. The key point here is that the resulting swords had such an extraordinary combination of hardness and flexibility that Crusaders sought to acquire them.

The secret of Damascus weapons lay in their composition, which, as mentioned, was not entirely original. To manufacture a sword using this method, the steel had to undergo a refining process that caused microparticles of carbide (compounds of carbon and another, generally more electropositive, element) to precipitate in bands across the blade, creating a pattern similar to fingerprints. This was what gave the swords their excellent qualities; according to legend, a Damascus steel sword could cut a piece of silk in midair or even slice through rock without losing its edge.

Damascus steel
A modern blade made of Damascus steel. Credit: Olmstead / Public domain / Wikimedia Commons

The metal used could be local, but it was also imported from the southern Indian subcontinent, where wootz steel originated, reaching the Near East through trade. Naturally, wootz steel was also crucible steel and had a high carbon content. During the iron smelting process, which used charcoal made from bamboo and other plants, pig iron and glass were added, helping to draw out impurities as the material cooled. These impurities alternated with small steel buttons or pearls containing 1.5% carbon, which were separated from the slag to form ingots, from which bladed weapons were forged.

The wootz steel technique dates back to antiquity: furnaces have been found in Sri Lanka (Samanalawewa, Anuradhapura, Tissamaharama, Mannar, and Samanalawewa) and India (Golconda, Karnataka, and Tamil Nadu). The oldest ones, dating to around the 5th century BCE, were positioned strategically so that their fires were naturally fueled by the monsoon winds (from the west). Once the desired temperature was reached, magnetite was placed in a crucible with glass and carbon, and the mixture was put into the furnace. After the material melted, hematite was added. The slag was then removed through hammer forging.

Maritime trade across the Arabian Sea allowed swords first and then wootz steel to reach the pre-Islamic Arab world, where poetry contains laudatory references to these weapons, then known as muhannad or hendeyy. The next stop was Damascus, which had a significant forging industry and adopted the technique, further perfecting it. In fact, the phrase “Indian reply” even became a popular expression, referring to a slash made with one of these swords. Al-Idrisi, the famous 12th-century traveler and cartographer from Ceuta, considered the hinduwani or Indian steel to be the best in the world.

Damascus steel
Band patterns of wootz steel (left) and Damascus steel (right). Credit: Rahil Alipour Ata Abadi / Wikimedia Commons

This was not unique in history, of course. In antiquity, Noric steel was also highly regarded, named after Noricum (Noricum in Latin), a federation of Celtic tribes that inhabited the region forming a triangle between present-day Bavaria (southern Germany), Austria, and Slovenia. In the first quarter of the 1st century CE, Claudius incorporated Noricum into the Roman Empire, with its capital in Virunum. The region’s mountains provided iron, giving rise to an industry that produced long swords, which, according to Ovid in Metamorphoses, had extraordinary hardness and were even adopted by some Roman auxiliary units.

Similarly, Japan had its own tradition with tamahagane, a steel derived from iron sand, which, in its highest-quality form (masa satetsu), had a carbon percentage between 1% and 1.5%, though in practice, it often exceeded this limit, lowering its quality (akame satetsu) and making it essentially cast iron. For this reason, Japanese swords were often fragile. Once the smelting process was completed—taking between one and three days—the tatara (a clay furnace) was broken to extract the resulting block, with the best steel, the silvery outer layer, being reserved for sword making.

Returning to the main topic, if it arrived by sea in the Middle East around the year 1000 and in Syria a century later, by land (crossing Turkmenistan and Uzbekistan via the Silk Road), it had already reached Russia between the 8th and 9th centuries AD. There are references to bulad (steel) in some medieval legends about the weapons wielded by Genghis Khan’s warriors, which were presumably made of wootz steel. Apparently, the Russian version included a novelty—a liquid derived from an herbaceous plant called stalnik (Ononis spinosa), in which the finished sword was immersed before being left to dry and harden in the wind while galloping.

Damascus steel
A fragment of tamahagane. Credit: Loulasedna / Wikimedia Commons

It was not until 1838 that Pavel Anosov, a military engineer and metallurgy expert, after a decade of studying Damascus steel—which he considered inferior to wootz—managed to reproduce a technique with results comparable to those of ancient India and Sri Lanka using ferrite (pure iron), cementite (iron carbide), and carbon. The key lay in the amount of the latter and, above all, in cooling the mixture very slowly to allow the precipitation of micro-particles between the ferrite crystals, thereby creating the characteristic bands. Bulat was used in Russia for cannon manufacturing until the second half of the 19th century when the Bessemer industrial system prevailed.

The wootz steel technique was also known in Europe in the late Modern Age, from the 17th century onward, when it was introduced by numerous travelers who had visited southern India (Mysore, Golconda, the Malabar Coast). In fact, it is believed that the word “wootz” originated in England as a corruption of ukko or perhaps hookoo, the respective Kannada and Telugu terms (Dravidian languages spoken in India). In England, as in Russia or France, there was little tradition of working with steel containing carbon alloys, so this novelty was of great interest.

The renowned naturalist Sir Joseph Banks, who sailed with Cook, received a sample of wootz steel sent by the Scottish physician Helenus Scott and analyzed it in detail in an attempt to unravel its secret. Subsequently, edged weapons—particularly those of the highly valued Sikh warriors—sent by the rajahs to the 1851 Great Exhibition in London were also studied. However, the British failed to replicate the Indian process and achieved no results until physicist Michael Faraday—whose father was a blacksmith—had a serendipitous success by adding alumina and silicon to the crystal while working in a cutlery factory.

Damascus steel
Blacksmiths coating a steel ingot. Anonymous engraving from 1891. Credit: Public domain / Wikimedia Commons

Nevertheless, this does not mean that Europeans lacked high-quality steel. Spanish steel, also known as Toledan steel because Toledo had been the peninsula’s main arms production center since Roman times (Hannibal Barca acquired the famous Iberian falcatas for his army there), was famous for producing blades of extraordinary hardness and flexibility. This was achieved by crafting them with a wrought iron core wrapped in a layer of steel, made by combining two types of steel with different carbon contents—one high and one low. The tradition continued in the Middle Ages and flourished in the 16th and 17th centuries, when Spanish swords were held in the highest regard, along with German swords from Solingen and Passau.

In other countries, they relied on Swedish iron, which had very few impurities and was heated with charcoal in a furnace for a week, forming ingots covered in bubbles. These ingots were then reheated to facilitate forging, during which their carbon content was reduced, resulting in what was known as blister steel (cutting steel). This technique, known as the cementation process, made Sweden the leading iron exporter and was quickly adopted in Germany and England. The latter replaced it with the technique developed in 1740 by Benjamin Huntsman, a watchmaker searching for the right steel for his timepiece mechanisms.

Huntsman’s technique involved placing iron with kaolin in a crucible and heating it to very high temperatures in a coke-fueled furnace. Coke, a distilled bituminous coal, had its water and tar removed until it consisted of 90 to 95% carbon. Carbon was essential because it allowed the transformation of iron oxide into iron—since in its natural state, this mineral oxidizes upon contact with the atmosphere due to oxygen. Heating the oxide with carbon enables the production of iron with a certain degree of purity, though with high concentrations of carbon. If these exceed 4% or 5%, the resulting alloy is not steel but pig iron; steel must have around 1%, so it requires a second treatment known as steelmaking.

During his invented process, Huntsman added pieces of blister steel and removed impurities by injecting air, which caused them to surface as foam. This method produced ingots that became the foundation of British steelmaking, particularly in the city of Sheffield. Sheffield’s production increased from about 200 tons of steel per year to 80,000—half of all European steel output—making it, in a way, a modern version of Sri Lanka’s Samanalawewa, where archaeologists estimate thousands of steelworks operated until approximately the 4th century.

This article was first published on our Spanish Edition on February 14, 2025: Wootz, el acero originario del sur de la India que fue el origen del famoso acero de Damasco

SOURCES

S. Srinivasan y S. Ranganathan, Wootz steel: an advanced material of the Ancient world

B. Sasisekaran y B. Raghunatha Rao, Technology of iron and steel in Kodumanal-An ancient industrial entre in Tamil Nadu

John Verhoeven, Pattern formation in wootz damascus steel swords and blades

Wikipedia, Acero wootz

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