During the Crusades, the European armies returned to Europe with stories of all sorts of booty. Much of this was in the form of goods unavailable in Europe. These included a variety of dies, silks, spices, feathers, fabrics, candles, books, and other luxury goods, but the most valued of all the prizes in the Crusades were the swords used by the Muslim elite. These were far sharper, stronger, and more flexible than those of the European armies, and this superiority was naturally exaggerated in legends to the point where it was claimed that they could cleave thick stone, or more elegantly, cut through a silk ribbon which was dropped over them with only the ribbon’s own weight pushing the sword through.
Swords of Damascus steel were characterized by complex “watered” patterns on the surfaces of the metal. Such patterns can result from a number of different metallurgical processes, but is generally an indication of the presence of numerous layers of metal of varied strength, hardness, and toughness. By combining multiple metals in a single blade it is possible to reach a more optimal trade-off between desirable properties of a metal than would be possible if the single metal that best exemplified the desired properties had to be selected. The general principle at work here, that of the optimality of specialization, can be seen as analogous to that of the productivity gains associated with the division of labor.
In addition to this mixing of layers, which is common to several other forms of superior blade manufacture such as pattern wielding and the folding of a katana, it is often suggested that more exotic materials were present in Damascus steel. Proposals include vanadium, tungsten, and even unusual concentrations carbon nanotubes. Vanadium and tungsten steel alloys can be much harder than any pure carbon steel can be, while carbon nanotubes have hundreds of times the strength to weight ratio of steel. They are produced in any extremely high temperature environment where iron or nickel is present along with much higher concentrations of carbon, and thus should be present in all steel at some concentration, but the concentration of carbon nanotubes could have been increased by superheating charcoal with just a trace of iron dust prior to mixing it with iron in a crucible.
Damascus steel seems to have originally been forged in the vicinity of Damascus, a city in contemporary Syria, but this is not known for certain. The technique of producing patterned multi-steel ‘wootz’ seems to have originated in India or Sri Lanka before the third century BC. It is not known whether the superiority of Damascus blades was primarily the result of the use of ‘wootz’ or of further refinements, nor whether the raw materials for Damascus blades were manufactured in the Middle East, in India, or in contemporary Turkmenestan, where apparent ‘wootz’ crucibles have also been found.