Caring for stainless steel knives to maintain their sharpness longer

Different types of materials are used in the manufacture of knives, depending on the final product’s performance, resistance to external factors, and working lifetime. The requirements for the main parameters of an industrial knife relating to abrasion resistance, impact resistance, or thermal load are usually more stringent, which is why they are manufactured using such materials as ceramics or cermets. For daily-use, knife steel is the most common choice, for which the most demanding (in terms of maintenance) high-carbon steel and various stainless steel grades can be used. This is particularly desired when the tool is exposed to contact with water

What is stainless steel, and how should a stainless steel knife be maintained?

Stainless steel is an alloy with chromium, and often nickel and molybdenum, as additives. Due to their presence, the material becomes less susceptible to corrosion. Under normal conditions, it generally means that a blade is well protected against water or moisture damage. It is important to remember, however, that it is closely dependent on the type of steel, as some alloys, known as stainless alloys, may oxidise to a certain degree. To protect knives against rust, after moistening the blade, we should always wipe them dry and additionally apply mineral oil to their surface from time to time to penetrate into the metal surface roughness and form a layer that efficiently expels oxygen. A similar situation occurs when steel is protected with an additional anti-corrosive coating. This applies, however, to the most expensive cutting knives, so if we use medium- or low-class products, then we should exercise utmost care and take periodic care of the blade. It is also important to remember that we may need to take proper care of the blade and, in clasp knives, their main axis.

Properly sharpening a knife

To obtain the required sharpness, it is necessary to grind the surfaces forming the blade. The main parameter to look after is the angle between these surfaces. This depends on the type of material used and the tasks for which the knife is designed. For daily use, an angle of between 15 and 17 degrees per side is usually suitable. If soft items are being cut and a high degree of precision is required, then the angle may be reduced, even to several degrees. We should remember that the lower the angle, the higher the susceptibility to nicks. For sharpening, we need sharpeners with different grits. A sharpener with the lowest grit is used at first to remove more material. Then a medium grit is used, and for finishing the highest grit is used, which has the most delicate effect. Depending on our manual skills and the importance of the knife’s sharpness, we can use a V-type sharpener or a flat grindstone, although using the latter can be very challenging. Remember that whetstones should be moistened with water or oil. The sharpening technique is also based on the blade’s cut; sharpening knives with a one-sided and flat cut is the simplest. Blades with a concave or convex cut can be more troublesome, yet they are used for special-purpose knives. Special knife sharpening systems have been designed for those who require a high quality finish. In these systems, the blade is set in the vice and remains stationary, while the whetstone is moved along a guide to give the best results.