If there is one constant amongst professional and home chefs, it’s the belief that the single most important tool to possess is a good knife. A sharp knife is easier to control, requiring less force that might lead to slippage and hand injuries. It slices through foods more cleanly, requiring less effort to cut and chop. Professional chefs prize their knives so highly, they carry them to and from work to ensure they always have their preferred tools on hand.
But what differentiates one knife from another? What is the reason for one knife being priced at $20, and another at $200? Most often, it comes down to its material: when it comes to knife construction, the type of steel will have the greatest impact on its performance.
First, we need to determine the qualities that make up a good quality knife. Some of the most important characteristics include:
• Corrosion resistance: prevention against rust and pitting
• Edge-holding capability: the length of time a knife can keep its sharp edge
• Strength and ductility: the knife’s ability to absorb force without damaging its shape
• Hardness and wear resistance: the toughness of the knife, along with how frequently it can be sharpened
• Workability: the steel’s ability to be formed into the desired knife shape
The difficulty lies in producing a knife that fulfills as many of these criteria as possible, because they can conflict with each other. A stainless steel knife with great edge retention will require a lot more effort when it comes to sharpening. Ductile knives have good tensile strength, which allows them to flex during cutting and therefore avoid breaking – but they also need regular sharpening since they lose their edge more quickly. Added chromium or vanadium in the steel will boost a knife’s corrosion resistance but make it easier to snap with too much lateral pressure.
So the construction of knives depends on balancing these factors, while producing the best type of knife for a consumer’s needs. With these criteria in mind, we can examine the best choice of metal for knifemaking.
Carbon Steels
Carbon steels are just as the name describes, steels where carbon is the main alloying element. A higher level of carbon produces a very hard and wear-resistant steel. This is highly desirable for knifemaking, because that strength and hardness means the knife can be ground to an acute degree of sharpness. The knife will also retain the razor edge for an extended time during its use.
However, that sharpness often comes at a high sticker price, plus the added fuss of regular maintenance. High carbon steels are more prone to rusting than other types of steels, which means they will begin to develop rust if left wet. In humid environments (either due to climate or a small, steamy kitchen), it may be recommended to keep the blade oiled between uses to guard against rust. The high carbon content also reacts to acidic foods such as tomatoes and onions, darkening the blade and leaving a patina. While this patina does protect the steel from corrosion, some users may find it unsightly. If so, washing the knife and patting it dry immediately after each use will help preserve the blade’s shine. With careful maintenance, a carbon steel knife can be a lifetime investment; its hardness and durability will allow for many years of use.
Tool Steels
This class of steel is typically alloyed with four main elements: chromium, tungsten, vanadium, and molybdenum. This alloy mixture produces a steel that is extremely hard and resistant to abrasion and deformation. Because of this toughness, it is most often used in machinery for extruding, pressing, and cutting other metals, which is why it earned the name “tool steel”.
When used for knifemaking, tool steel generally goes to the production of utility and combat knives. Like high carbon steels, tool steels are quite hard which means they can be ground to an extremely sharp edge. But it also has pitfalls that make it less suitable for the regular wear of cooking knives: a propensity to rust, increased risk of snapping with lateral pressure, and the edge can develop nicks and chips. The alloying elements help protect against corrosion, but depending on the knife’s use, it may not always be convenient to clean it immediately which will contribute to its wear. But it will stay very sharp for a long time, making these knives valued assets to soldiers and hunters in the field.
Stainless Steels
Produced by adding chromium and other elements to steel, stainless steel offers a high degree of corrosion resistance. While it can begin to rust if treated carelessly, a stainless steel knife is easier to maintain compared to a carbon steel knife. Keeping the blade clean and dry will generally be enough to prevent against corrosion and darkening. The chromium in the alloy also gives the distinctive silvery sheen of stainless steel, and helps resist tarnishing.
The main disadvantage of stainless steel is that it is a softer and more malleable material than carbon steel. Carbon steel’s extreme hardness gives it the ability to be honed to a razor edge. In contrast, a stainless steel knife is more difficult to sharpen, is more prone to deformation while sharpening, and is unlikely to reach the same peak sharpness of a carbon blade. However, that softness may not necessarily be a drawback. Most home cooks don’t require a super-sharp knife, and a stainless steel knife does keep its edge for quite some time. Its ductility also means less risk of chipping the blade, since the softer steel is better able to absorb force during chopping. The affordable price of most stainless steel knives, along with their low maintenance, is why they are the best-selling option on the market.