How good is your knife?
Everyone likes to work with a good, sharp knife, but often you only realize you’ve been working with bad knives for a long time when you start using a really good knife. That is why we are going to give some useful advice to help you define the type of knives you work with.
look at the knife
Before you start checking the sharpness, it’s important to really look at the knife. It is difficult to explain on paper how to recognize a good knife, but there are some points to pay attention to.
Look at the thickness of the knife. The illustration above shows two carving knives.
At first glance both knives look alike and their biggest difference seems to be the handle. However, there is a much more important difference: the thickness of the blade.
To make that difference visible we have sharpened both knives. That shows the cross section of the knife.
The top knife blade is 1.4mm thick with the thickness decreasing to 0.35mm at the cutting edge.
The bottom knife blade is 3mm thick at the top, still 3mm in the center, then tapers to 1.5mm at the edge.
To cut easily, the knife must be thin. The thickness of the edge largely defines the sharpness of a knife. Even if the knife needs sharpening, a thin knife will still cut reasonably well.
0.35mm is the perfect thickness for a carving knife. For a chef’s knife that exerts more pressure, the thickness can be a bit more: 0.45mm is still perfect.
The thickness of the spine depends on the height of the knife. For chef’s knives it can be a maximum of 3.5 mm and for carving knives from 1.5 mm to a maximum of 2 mm.
*There are two exceptions to this story: butcher’s hatchets and single-edged Japanese knives.
Butcher axes need to be strong, so they are sharpened to a few millimeters thick and convex. Debas and Sashimi knives are Japanese knives, intended for very fine cutting of vegetables and meat. Those knives are sharp on one side and very sharp. Since they are only used for cutting thin slices, the thickness of these knives is not an issue*.
Blades that are too thick can also be made by sharpening the knife frequently. Since a blade gets thicker towards the back, the edge will get thicker as you sharpen the knife frequently. If you treat your knives with care and maintain them with a ceramic rod, for example, this won’t happen as soon. Even with professional use, this knife can be used for a decade without problems.
*If you have your knives sharpened regularly by a professional, your knife will wear out much sooner.
Professional sharpeners sharpen the knife electrically and remove a lot of material. There are also sharpeners that thin the knife, but then you have to be careful that the knife is not too thin*.
If there is no damage to fix, or an edge that is too thick, do not have your knife sharpened electrically, but do it yourself with a ceramic rod. It’s much easier than you think and faster than going to and from the sharpener.
A knife can be too thick, but it can also be too thin. Cheap knives are usually made of band steel with a spine that is too thin. A knife must be stable (sturdy) enough for its purpose. Fillet knives and flexible boning knives are the obvious exceptions.
Only specialty knives, such as bread knives and tomato knives, need to be serrated. Are all the knives in your set serrated? That is the sign that the knives were made of a lower grade of steel. They are then serrated to mask the lower steel so the knife will continue to cut a bit (or be used as a saw).
The jagged edges produce a lot of friction while cutting and a messy result. A knife made of a good quality steel does not have to be serrated to stay sharp, and cutting will be much easier than with a similarly serrated knife.
Visual state of the knife
After we have defined the type of knife in the previous steps, we examine the state of the knife. We go from big to small.
Broken tips, “chips” on the blade
Look carefully at the sheet. When there are broken points, or chips on the blade, they do not always indicate poor quality, but often a bad owner.
A good knife is always made of hardened steel and is therefore more brittle than soft steel. You can prevent knives from getting damaged by storing them carefully. Prevents edges from colliding. A knife block or magnetic stripe are perfect options. If you still want to store them in a drawer, be sure to protect the blade with a lid.
Another cause of point breakage and blade chips is often loosening or cutting. Never use a knife as a screwdriver or lever and only use a blade for cutting.
Tips and parts of the blade bent
A lot must go through to bend a good quality knife. The tip will bend if dropped, and cutting bones with a chef’s knife will also bend parts of the blade. With normal use it is not possible to bend a good knife. If your knife still has a bent blade or tip, this is usually a sign of poor quality steel.
Sharpening: visual check
If the above checks show that you have a good knife, it makes sense to check the sharpness.
Hold the knife with the edge pointed at a light source and check to see if the light reflects off the edge.
If it sees light along the entire length, your knife needs to be sharpened. If the light is visible in some places, it is not necessary to sharpen the knife immediately. It depends on what you want from your knife.