Damascene Swords
Damascene swords were highly sought-after articles in the age when sharp blades ruled the world. Their reputation stemmed from the way in which they were made and from the problems that other sword-smiths had discovered.
A sword is, basically, a long, flat strip of steel, sharpened on both sides, which you swing to cut pieces off your enemy. It is obvious that the sharper the sword, the better it is for its purpose. Unfortunately hard iron that will retain an edge is extremely brittle and a sword which, while splendidly sharp, shatters the first time it encounters any resistance a hard-headed opponent or one wearing armour is pretty useless. A tough sword, which bends rather than breaks, does not take an edge and is little better than an expensive club.
It all has to do with the atomic structure of iron. Pure iron is very hard to melt, requiring temperatures over 1500°C to turn completely liquid. As a result early smiths could do no more than soften it and then pound it into shape, a process that had the additional benefit of expelling the slag produced during the smelting. As a consequence of the work that had to be done to it, this soft iron became known as "wrought" iron.
Smiths discovered, however, that iron smelted directly over a fire, instead of in some sort of crucible, melted at a much lower temperature and was very hard. Today we know that the crystalline structure of the metal is modified by the inclusion of carbon from the charcoal used to smelt the ore. Cast iron, which, contains 24.5% of carbon, melts at about 1300°C. It is extremely hard and brittle, which makes it unsuitable for swords!
Steel contains about 1.5% carbon, but keeping the carbon to that level requires great skill and the techniques were kept a state secret by successful countries. (European smiths did not even discover how to reliably produce cast iron until the early sixteenth century.) The result was that various techniques were invented to combine the qualities of the two types of iron cast and wrought one of the most successful of which was devised by the smiths of Damascus.
According to the books which describe what we know of the highly secret process, the swordsmith would start with two strips of iron, one cast and one wrought. He would heat these and then, putting one on top of the other, he would hammer them out flat and long, thereby welding them together. After some more heating, he would then bend the long strip in two and again hammer and weld the metal sandwich together. After several repetitions you would have a long strip of metal made up of many alternating layers of hard and soft iron.
Those astute enough to go on our tour of Turkey will visit the famous Topkapi Palace Museum in Istanbul. Among the fabulous objects of display are a number of swords. Some of these were captured in war and are not worth a second glance: others belonged to various of the Turkish sultans and you would naturally expect these guys not to stint themselves when it came to weaponry. Adjust your bifocals and peer closely at these swords. You will see dozens of thin black wavy lines running down the length of the blade. The black lines represent the "join" of the iron sandwich and some idea of the amount of work involved in producing such a sword can be gained by counting the number of lines and then looking at the thickness of the blade!
The quality of such swords can be judged by the old legend of the meeting between Saladin and Richard the Lion-heart. According to the story the two rulers met under truce and exchanged courtesies. Saladin fed his guest on oriental sweetmeats and gave him sherbert to drink and before long the two men fell to comparing their favoured weapons. Richard called for an anvil to be brought and when it was placed in front of him he took a two-handed grip on his best battle axe, raised it high above his head and then brought it down with a thump, cutting the heavy anvil completely in two. Saladin smiled politely at this exhibition of brute strength and took the filmy silk scarf off the face of a nearby slave-girl. He drew his sword, a fine Damascene weapon, and then tossed the scarf lightly into the air. His sword flashed, apparently missing the scarf, which continued to fall undisturbed to the earth. He gestured to Richard to pick it up and the astonished Englishman discovered that it had been cut cleanly in two by the sultans razor-sharp blade!
Al-Biruni, an Arab scholar who lived from AD 973-1050, records details of another, easier way of producing fine steel. He said, "The mixture of narm-ahan and its water, which is the substance which flows when the narm-ahan is purified, is fuladh. The area of Herat is especially noted for it and it is called baidat (eggs) on account of its shape. The eggs are long and round-bottomed, following the shape of the crucibles, and from them Indian swords and others are fashioned." Elsewhere al-Biruni referred to the "water of narm-ahan" as dus.
Other Arabic manuscripts reveal that narm-ahan is wrought iron and fuladh is steel, but what is dus or the "water of narm-ahan"? Excavations in the ruins of ancient Merv, a town in northern Persia, may have revealed the answer.
Georgina Herrmann, of the Institute of Archaeology at University College, London, began excavating at Merv in 1992. The city was an oasis in the Kara Kum desert and an important trading post on the Silk Road. Ms Herrmann expected to find plenty of evidence of wealth as well as gaining insights into the lifestyle of medieval city-dwellers in Asia. What she did not expect was evidence of a large metal-working industry far less evidence for steel production!
The first discovery was interesting enough: broken furnace walls and the fragments of shattered crucibles coated with glass-like slag. John Merkel, a metallurgist from the same university, investigated the slag in order to find out what metal was being worked and to his surprise found tiny droplets of steel, 0.3 mm in diameter, held by the slag.
This presents historians with something of a dilemma, because Merv is not the first place you would think of when talking about metal production. There are no ore deposits nearby, the deserts of Turkmenistan are not noted for their vast fuel supply, there isnt even any suitable kaolin clay for making the crucibles! The answer may lie in the discovery that the smiths of Merv used and perhaps invented the smelting technique mentioned by al-Biruni.
Known as "co-fusion", the technique is to place pieces of wrought and cast iron in a crucible and smelt the two together. As the temperature climbs to 1200°C the cast iron melts and the wrought iron softens. Some of the carbon from the cast iron diffuses into the wrought iron, producing true steel at a temperature several hundred degrees lower than the 1500°C required to cast steel. Dus or "the water of narm-ahan" is molten cast iron.
Al-Biruni went on to describe the results of the process: "Either the narm-ahan and its water melt equally in the crucible and unite so that one cannot distinguish the one from the other, in which case it is good for files and the like ... or alternatively, the melting qualities of what is in the crucible vary, so that the two do not mix completely but on the contrary are separate in their parts from one another. ... This is called damask."
In other words, contrary to what the books say, our swordsmiths may not have started out with two strips of metal, but rather with a semi-molten mix of the two irons.
