If you are thinking about buying one of my blades, or perhaps you are thinking about having something custom made, you might wonder: ‘which kind of steel should I go for?’ That is a valid question to ask. Especially considering that the type of steel will have a significant impact on the price.
Let me start by saying that no matter which steel you end up using, I only work with high quality steel, and I will not use a steel if it would not be suitable for its intended use. No matter what you end up with: if it leaves my shop it will be a good choice.
So with that out of the way, let’s look at some of the things I work with.
The most basic steel to use is carbon steel. It is basically Iron with a certain percentage of Carbon in it, and possibly other alloying elements to control certain properties of the steel. Carbon steel is excellent at forming a good cutting edge.
There are broadly 2 types of carbon steel: through hardening and shallow hardening. What this means is that when steel is quenched as part of heat treatment, some types of steel harden easily and all the way through, and others don’t.
A lot can be said about when to use which steel. In both cases the edge will be hard, sharp, and good. Only with through hardening steel, the entire blade will be hard. With a shallow hardening steel, the thicker part of the blade, or the parts that were coated with clay during the quench) will still be soft. Where the hard and soft steel touch each other, there will be a visible line. This line is called a Hamon and is typical for samurai swords for example.
For the types of knife and razor that I make, this aesthetic is the only relevant difference between those 2 types of steel. So if you go with a carbon steel blade, the choice for either type of steel is simply personal preference for the aesthetic.
Through hardening steel
Shallow hardening steel with hamon
Damascus is a term that carries a lot of baggage. In ancient times, the term ‘damascus’ was used for a type of crucible steel that goes by the name ‘wootz’ today. I will talk about wootz a bit further down.
In modern times, the term ‘Damascus’ has been used for steel that is made from different layers of steel. The process starts with a stack of steel bars / plates. Some of these will contain Nickel, while the others don’t. This stack is then forged together, and then folded, twisted, and otherwise manipulated to distort the internal layer structure. At the end of the process when the blade is ready, it can be etched in acid. The layers that contain Nickel will turn bright, and the layers without will turn dark. This can create wonderful patterns, ranging from simple parallel lines to very complex structures.
Typically, my Damascus is made from O2 tool steel and 15N20 tool steel. For the things I make, this is the best combination to be made. However beautiful the pattern may be, in terms of performance, the resulting blade will be identical than if it had been made just from O2 steel. All the folding and manipulation only serves aesthetical purposes, nothing more.
The possibilities for patterns are endless.
Wootz was originall known as Damascus steel, Bulat, or others. It has a fascinating history. It was being made in the middle ages, before people understood metallurgy or alloying elements. It’s discovery was probably a fluke, a chance outcome caused by working with ores containing just the right mix of elements, and then working it the right way.
Wootz is made by smelting iron, carbon, and alloying elements in a crucible. When the crucible cools down, the steel forms dendrite carbide structures. If the steel is then forged, thermal cycled and heat treated just right, these structures will be in the finished blade. If the blade is then etched, these structures will become visible.
This type of steel has always been known for its cutting properties. The reason is that those carbides are thin and much harder than the steel surrounding it. As a result, at a microscopic level the very edge will be sprouting microscopic teeth that act as serrations during the cutting action. To the naked eye, this is invisible. From the feedback I have received, wootz edges shave better and retain their edge longer. Note that all my razors shave well and keep their edge for a long time. It’s just that wootz is just a little bit better than other steel.
Tamahagane is the steel known from samurai swords. It is steel that is made by building a big charcoal fire in a kiln, and then adding layers of iron ore and carbon for a long time until everything has burned out. At the bottom of the kiln, there will be blobs of crusty steel with high carbon content.
This type of steel tends to be chemically very clean (just iron and carbon without almost any alloying elements) but with a lot of slag and inclusions. The pieces of tamahagane are forged together, and then drawn and folded again at very high temperature. This process is repeated between 7 and 10 times, after which the steel should be solid, and the carbon content homogenized.
In fact, the process is similar to creating damascus steel, except we are folding just 1 type of steel over and over, instead of using different kinds of steel.
If the blade is etched after it is finished, this folding pattern becomes visible. Because it is the same steel, the pattern will be more subtle than the typical ‘light / dark’ damascus pattern that comes from using different kinds of steel
High alloy steel aka supersteel
All of the steel mentioned so far is low alloy steel. It’s also possible to use knives with a high percentage of alloying elements. Such steel is called high allow steel, and is also commonly referred to as supersteel, wunderstahl, unobtainium, or several other colorful names.
These steels are much, much more difficult to forge, heat treat and grind. And they do not necessarily result in a knife that is objectively sharper. But they will have a significantly longer edge retention, and will be much more wear resistant.
For razors, there is not a whole lot of benefit, because of how razors are used. But for kitchen knives you can certainly argue that the edge sees a lot of force and abused. So for those kinds of knives, that would be a good thing.