Learn the basics about different knives and steels
From time to time, customers return to us with a knife that has been damaged to the edge or tip. Although this happens very rarely, we feel that it is important to inform you about how to use your different knives and what the difference is between different types of steel. In this blog post, we will therefore explain the difference between soft and hard steel and the different characters in each steel. We also explain what chipping is and how you can easily fix a chipping on your own.
Hardness of steel
When measuring a blade to find out its hardness, you measure with a durometer and the result is stated in the unit HRC (Rockwell). Good knives have between 55 and 65 HRC, so even small differences in HRC can mean a big difference in hardness. This does not necessarily mean that a soft blade is worse than a knife with a high HRC. It all depends on what characteristics you are looking for in a knife. A soft blade with 54 HRC is easier to grind. The grinding angle is usually around 25 degrees and you do not have to worry about doing it perfectly, thanks to the soft edge, it is easy to reshape the grinding angle until the knife is sharp. The final sharpness of a knife with low HRC rarely becomes as sharp as a knife with high HRC, and the edge does not keep its sharpness for as long.
What is the difference between soft and hard steel?
Soft steel — our standard carbon steel
Our standard carbon steel, which contains about 0.8% carbon, is what we call soft steel in this blog post because it contains a lower proportion of carbon content than our harder UHC steel (Ultra High Carbon). For example, if you chop a soft blade into a rock, plastic deformation will occur, which means that the steel chooses to dent and react by being deformed when it is subjected to resistance that is too brutal to the knife's egg.
Hard steel — our UHC steel
Our UHC steel (Ultra High Carbon) contains about 1.8 - 2.0% carbon and is what we call hard steel. Roselli's UHC steel is considered to be one of the toughest steel grades in the world and these blades measure around 62-63 HRC. This strength enables extreme sharpness and an edge that stays sharp for a very long time, even longer than any other traditional carbon steel blade.
Our knives with hard blades can be sharpened at a much steeper angle and still maintain their sharpness during use. When a hard steel is subjected to a resistance that is too brutal to the edge of the knife, an injury can occur and achip comes loose. A hard steel does not have the same chance of being deformed as a soft steel, and will instead be broken. This is called chipping, and results in getting everything from a small notch in the blade to a small shard that comes loose.
Watch our video below showing what deformation and chipping looks like.
What is chipping?
When using one of Roselli's UHC knives, the edge should always be in motion when you cut. Under no circumstances should you push the blade through anything without the edge moving. Also, do not twist or wiggle the blade. If you press, twist or wiggle the blade, you expose the edge to a lateral strain. An edge usually withstands quite a lot when it cuts straight from the top down, while moving forwards or backwards. But with a lateral force there is only the edge, and no goods that capture and absorb the force. The hard edge will therefore flex as much as it can, and when the load becomes too much, a chip will come out of the edge (so-called chipping), or a piece of the tip will break off.
Chipping is not due to material or production defects, even though it may look like that – but is part of the steel's natural properties. To repair a chipping, you need to grind to a new edge. If you are not sure how to do this, you can read more under our Care & Repair guide. You can also send us your knife for a free sharpening. Click here.
Which steel should I choose?
All knives have different uses to serve. If you are more used to exposing your knife to more resistance and believe that the sharpness of the knife is not so significant, we recommend that you choose one of Roselli's standard carbon steel knives with softer blades. If you want a sharp knife that stays sharp for a long time but requires a little care and caution, you should definitely not miss owning one of Roselli's UHC steel knives (Ultra High Carbon).
Read more about which knife to choose >