Until recently, wootz was largely a part of history, a mysterious metal with legendary properties. First produced in the India early in the first millennium AD, the art of making wootz and forging it into blades was refined and continued until the 1700’s. The center of production was in India, although some was produced in other areas of the Central Asia, and the most famous of the wootz blades were forged in Persia. It seems that the wootz ingots were mostly produced in India, but that the forging of the ingots was done by smiths throughout a much wider region.

The art eventually died out, possibly as a result of changes in iron ore sources. Various attempts were made, mostly in Russia and Europe, to revive the process. These were in some cases successful in yielding steel with the characteristics of wootz, but none of these attempts yielded a process that was consistently repeatable. Thus the mystery of what made wootz tick went on…until near the end of the 20th century. It was during this time that several individuals and teams around the world were successful in deciphering the wootz mystery once and for all. Perhaps the best known of these was the team of Pendray and Verhoeven, a bladesmith and a metallurgist, both from the USA. It was through reading their work and that of others, along with nearly a year of experimentation of my own, that I developed my own technique for making wootz. It is essentially identical to the methods used for centuries in India, but has been adapted to the tools and techniques that are available to the modern smith. Unlike some smiths who advertise that they sell wootz or “technowootz” (typically just standard bar stock that has been heat treated to bring out its inherent alloy banding), my material is made by melting down carefully selected ingredients in individual crucibles, then slow cooling the resulting ingot to produce the necessary segregation in the steel. Finally, the ingot is carefully forged out to produce a bar of wootz, ready to dazzle the world.

Suddenly I have realized that I came this far without describing the ancient techniques or gone into the details of what creates both the visible pattern and particular characteristics of wootz. In the ancient world, iron was most readily available in two forms: wrought iron and cast iron.

Wrought iron was produced by heating iron ore (iron oxide) in a charcoal fire under somewhat oxygen-starved conditions. The oxygen from the ore was stolen to assist with combustion, leaving behind nearly pure iron with mostly silica as an impurity. The end result of the process was a spongy “bloom” of wrought iron, which could be consolidated through heating and hammering until it became solid and usable. At no point in the process did the iron become molten, meaning that it was “reduced” from its ore, rather than “smelted” from it. Wrought iron is practically devoid of carbon, has a melting temperature of around 2800F, and is actually softer than hammer-hardened bronze. This means that iron and bronze actually competed rather equally for many years…equal that is, until the discovery of steel.

Cast iron, despite how the name makes it sound, is hardly what a metallurgist would call iron. It is more like steel that has gone way off the deep end and cracked…which is exactly what it does if you try to forge it. Actually, this rather sums things up, in a way. Cast iron is produced by smelting iron ore at a sufficiently high temperature and in a sufficiently high-carbon environment to produce liquid metal. It is an odd thing about iron that the more carbon you add (up to a point), the lower the melting temperature becomes. Cast iron actually begins to melt around 2200F, which is substantially lower than the nearly 3000F that is required to melt pure iron. This made cast iron quite easy to produce in quantity, since that temperature was easily attainable in the charcoal furnaces in use way back when. The problem is that cast iron is horribly brittle when cold, and crumbles if you try to forge it hot. These together meant that it was unsuitable for weapons or tools, so an alternative needed to be found, something with the hardness of cast iron, but the toughness of wrought iron.

In different parts of the world, different solutions were found to this problem. Most iron working cultures eventually developed some form of laminating, first as a way to refine the poor quality materials, and then later developed further for the aesthetic value. Persia and India were just like everywhere else in this sense, but entirely different in that they also found a second solution. Wootz was probably accidental at first, but soon was developed into a booming industry that sold material throughout the Middle East. Here is the technique that they discovered.

It starts with a crucible made from fireclay, able to withstand the scorching temperatures found inside the blacksmith’s forge. The crucible is loaded first with specially selected and cleaned wrought iron bits. Next are added dry twigs or charcoal along with a few green leaves. On top of this were layered crushed seashells, and then the top of the crucible was sealed with more fireclay. Each of the ingredients had a specific purpose, although it is hard to know to what degree the ancient smiths understood those purposes. I will skip the wrought iron for the moment, since its purpose is fairly obvious. The dry twigs were there as a source of carbon, while some theorize that the green leaves were there as a source of hydrogen. Hydrogen helps carbon absorption, but I imagine that the leaves were more symbolic than anything else…maybe they were something of a garnish. We will never be entirely sure, since the ancient smiths were rather secretive. The seashells were there as a slag layer, which helped to purify the materials and also helped exclude oxygen. The final step of sealing the crucible was also aimed at excluding oxygen, but my own experiments have shown that this seal almost invariably

Once the crucible was filled, it was placed in a charcoal furnace, generally along with several other crucibles. In the early days of wootz production, the furnace was not hot enough to actually melt the metal. Instead the process, which at that point took nearly a day, would yield a spongy cake of super-carburized iron, which would later be forged out into a solid bar and eventually a weapon. As the years passed, the furnaces improved and the iron actually melted while at the same time requiring a firing time of only a few hours. It was important in both cases that the crucibles be allowed to cool quite slowly in the furnace to allow the wootz to “mature”. I am not knowledgeable about the structure of the early wootz, but the later wootz depended on the slow cooling to develop large dendrites…these are the same idea as the large ice crystals that form on glass in the winter, except in steel. In either case the forging was a drawn out and arduous process, since the material was of such high carbon content that it was very brittle and hard when hot. Repeated heating and forging reduced the carbon content somewhat, and more importantly broke down the large internal crystals to make the material more malleable. Forging proceeded until a blade was formed. Unlike steel, which is heated and quenched in oil (or sometimes water) after it is shaped, some accounts indicate wootz was heated to a dull red and then cooled in a swift jet of air. This supposedly left the material very tough, but the carbides

Unlike steel, which relies on its heat-treatment to yield a hard crystalline structure, wootz depends on bands of carbides for its hardness and edge-holding ability. But how do the bands of carbides get in there? These bands are what cause the visible pattern in a wootz blade, and for centuries they provided the Persian weapons with superior properties. Then, mysteriously, wootz manufacture began to disappear, and there are two basic theories to explain this phenomenon.

The first and most widely told is that something happened to the material itself. Blades forged from newly made wootz cakes no longer formed carbide bands. Smiths throughout the Middle East probably invented an entire new language of curses during this period, and rightly so. Even though the patternless wootz blades still performed exceedingly well, without the visible banding customers were unwilling to buy wootz weapons. The pattern and the performance were thought to go hand in hand, and no one knew enough of the secrets of wootz to say otherwise. Also, the weaponsmiths probably doubted their own swords after this point.

The first theory revolves around mines and iron ore. Each deposit of iron ore has particular impurities, and the mines used by the Indian smiths must have had a specific impurity (more on this later) that promoted the banding. Thus, without even intending it, the Indian smelters and Persian smiths were able to create a material that would become legendary around the world. But then, when the iron ore from those mines ran out and iron ore that lacked the key ingredients replaced it, the banding disappeared. Within decades the methods of producing wootz were lost, and the legendary material almost became simply mythical.

The second theory is that wootz, which had been the superior material for many centuries, was simply overtaken by the improved steels being produced by the 1700’s. Warfare was also turning away from sword on sword combat and moving towards gunpowder, so the sword itself was becoming a less important item year by year. In this environment the wootz industry simply “melted” away or atrophied like the human appendix. Soon it was forgotten and the secret of making wootz was gone.

Having delved slightly into the history, it is time to tackle some of the technical aspects of wootz. Carbon is the main ingredient that makes steel hardenable. I do not know the specifics well enough to explain them, but basically the addition of sufficient carbon to iron allows the steel to be “trapped” in a new crystalline state through heating and quenching. Steel has many different crystalline states that depend mostly upon temperature and carbon content. Hardened steel is referred to as martensite. All steels become austenite above their “critical” temperature, and most steels exist as pearlite in their cool, unhardened state. Needless to say, there is more to go into here than most of you are interested in…if you are interested, drop me an email and I’ll do the best I can to help you out.

Steels with less than about .8% carbon by weight exist as a mixture of ferrite (pure iron), and pearlite -a mixture of ferrite and cementite (iron carbide). At about .8% carbon by weight, a cool, unhardened piece of steel is entirely pearlite, while above .8% you have a mixture of pearlite and cementite. Basically, carbon in unhardened, cool steel exists only as iron carbide, but how the iron carbide is distributed changes as the carbon content changes. Once you pass the “eutectoid” point (.8%carbon) you begin to get free carbides rather than iron carbide distributed relatively evenly as in pearlite. This is a key aspect of what makes wootz different. With carbon contents ranging from 1.1%-1.8%, wootz has the potential for a very large number of free carbides. Having the potential is not the same as actually having them, though, which brings us to the next part of our little metallurgy lesson.

Carbon travels relatively freely through iron, as can be seen easily in the case of pattern-welded steel. If you use simple carbon steels, one high carbon and one low carbon, within a few welding heats the carbon content of the billet as a whole will even out. The reason that this is of interest is that carbon by itself will not remain segregated in the wootz ingot. It actually does start out somewhat segregated, but quickly diffuses throughout the ingot. So what makes the carbides segregate into bands if the carbon by itself will not? The obvious answer, but one which took centuries of research to discover, is that there must be another alloying element. This element needs to be one that will segregate during solidification, along with being one that will promote the growth of carbides. Verhoeven and Pendray discovered that this element, at least in the ancient blades, was generally vanadium. Vanadium is a strong carbide former, plus it segregates well during the cooling process. Even a small amount of vanadium will allow a wootz ingot to develop carbide bands if properly treated.

Today, through modern metallurgy, we know what causes the banding in wootz and can at least partially recreate the process of producing it. It is interesting to me, though, that so far there is no modern wootz on the market that looks as good as the original. It is as though we are still missing one piece of the puzzle, one secret ingredient or process, and it is something that we will only discover through a great deal of experimentation. Even with modern science being what it is, it is good to know that there are still a few secrets left to unlock.

If you are interested in further information about wootz, you can find a few web sites and articles online, or you can buy Figiel’s book, On Damascus, through Amazon.com or some specialty book dealers. The information on modern wootz in Figiel’s book is somewhat out of date, but his historical information is incredible. Beyond the information, the photographs are simply stunning.