Mad about Science: Damascus steel

By Brenden Bobby
Reader Columnist

It’s likely that you’ve heard the term “Damascus steel” at some point in your life — particularly if you’re a fan of swords. Beautiful marbled patterns rippling across the surface of a steel blade are a telltale sign of Damascus steel… or are they?

Metallurgy is a lot like baking: the collision of science and artform. The only difference is, you don’t want to eat what you make with metallurgy. This is a very complicated subject with thousands of years of history and discovery. To this day, as many as 44% of blacksmiths hold a bachelor’s degree. Don’t take anything I say in this article as gospel, because there are a lot of folks a hell of a lot more knowledgeable than me actively working on this stuff.

That being said, let’s learn about the manipulation of steel.

The creation and manipulation of steel is one of the most important building blocks of human civilization. Steel has a high melting point, between 2,500 and 2,800 degrees Fahrenheit. These kinds of temperatures cannot be achieved in a traditional wood fire or even in a charcoal-fed forge. Steel requires a crucible to focus enough heat to separate impurities from the metal and become soft enough to manipulate. This is currently accomplished on a large scale using an electric arc furnace that uses graphite tubes charged with electricity to heat a chamber filled with material to incredible temperatures. In the medieval era, this was impossible.

Patterned steel as we know it today is created by folding and hammering the metal to create layers, not dissimilar to folding and flattening filo dough to create a light and flaky pastry. A stack of steel billets would be heated and held together with a clamp and then hammered down. While it’s still hot, the blacksmith would use a power hammer or similar device to cleave the flattened billets in half and then fold the end of the stack back over the core and hammer it down again. If you start with eight layers, by folding it you create 16 layers. This can be done an unlimited number of times, but in the case of modern replications of Damascus steel, the process is generally repeated eight times.

This folding method was commonly applied in Japan to create everyone’s favorite pop culture sword: the katana. To this day, Japanese blacksmiths are world famous for their skill in manipulating steel to create some of the finest blades the world has ever known. There’s more to this than exotic mysticism — the core of Japanese metalsmithing is creating excellence out of necessity. What do I mean by this?

Japanese pig iron was a notoriously poor metal, particularly when blacksmiths were first learning how to create a furnace that could turn it into steel. Folding the steel was imperative in order to keep the weapons from being so brittle they’d break on first use. Japanese swordsmiths became the best at their craft because they had no alternative but to achieve excellence by using the poorest material available, as it was the only material available.

That being said, the idea that the katana is the greatest type of sword to ever be forged is a myth. The katana is an excellent slashing weapon that was perfectly suited to the environment in which it was used. Had feudal samurai and medieval knights come into contact with one another, the katana would have been a liability on the battlefield. European armor was designed to deflect slashing and piercing weapons at every level.

Regardless of what your anime-obsessed cousin may tell you, a human wouldn’t be able to deliver the required force to put a katana blade through a knight’s armor deep enough to deliver a fatal blow, if at all.

Damascus steel as we know it was likely developed somewhere in the Levant, which is the eastern Mediterranean coastal region of what we today call the Middle East. Named after the Syrian capital of Damascus, it’s unknown if this was where the technique was first developed or simply where the bulk of these weapons were sold. Unlike the Japanese katana, Damascus steel weapons display a unique pattern running throughout the metal, which is a byproduct of the pattern welding technique. To create waves and curves through the blade, smiths took an extra step by twisting the hot metal into a screw shape and then hammering the layers down over themselves. This wasn’t done simply for aesthetics, but was likely because the metallurgical technology for refining steel wasn’t advanced enough to completely separate impurities from the iron, leading to layers with different properties that were then welded together. 

There is a critical reason this isn’t seen outside of decorative blades today, and it’s the fact that we’ve developed more efficient methods to liquefy steel that allow it to be poured into molds with few impurities. A homogenous billet of steel is favored for uniform productions, as it’s less likely to crack or fracture unexpectedly under stress. Uniformity also makes things cheaper, allowing builders to rely on homogenized metal beams, rivets and other structures while buying multiples that are easily replicated.

The process for creating authentic Damascus steel was lost to time, though some close approximations have been achieved in recent years. True Damascus steel isn’t available outside of special archaeological and private collections, so if you see a patterned knife at your local store claiming to be Damascus steel, now you know the actual term: pattern-welded steel.

It still looks pretty cool, though.

Stay curious, 7B.