Blade thinning is the process of thinning the blade of a knife in order to achieve the optimal cutting ability of that blade – without compromising its structural integrity.
So why should you care?
It’s important because if you want superior cutting ability, you need the thinnest blade that your knife is designed for but there’s a precaution to be noted – if it’s too thin the apex of your blade can be easily damaged while using it.
The degree of the grind of the apex of a knife and its function must match
There is no use cutting rock hard frozen berries with a fine edged Japanese steel knife, for instance, or expecting the edge of your heavy duty cleaver to carve through meat like a French Chefs knife.
Within each knife category, therefore, there is an optimal range for the shape and thinness of each bevel and the degree of the grind of your blade.
In most cases, the blade should gradually taper down from the spine to the apex (or cutting edge) of the knife – unless it is a scandi grind edge which is sometimes referred to as a V grind (more commonly found on all purpose knives and bushcraft knives).
Steel yourself – The quality of your steel is important
In determining whether you should thin your blade, you also need to be aware of what type of steel your knife is made from.
Not all steels are equal.
If your knife steel cannot tolerate a thin blade then it doesn’t make sense to force that fate upon it. You will do more harm than good.
Allocated use is also an important factor
What is your knife going to be used for? A blade that is thinned to perfectly cut sashimi, carpaccio or fruit is generally going to struggle, or bend, cutting through hard cheeses or pumpkin.
When a knife is the optimal bevel grind and sharpness for its design, you will find that you have to apply almost no downward pressure to make it work as it should do.
West or East?- It makes a difference
Traditionally, most Western designed knives are shaped with a double bevel – meaning that the apex is formed like a V and it is even on both sides. You will usually find that the angles on these knives are between 10 and 20 degrees on either side
Japanese knives, by contrast, often have a razor sharp and much more acute angled single bevel (which also means they have to be designed specifically for either right handed or left handed users). These bevels are usually within the vicinity of 8 to 12 degrees.
Japanese knives can also have a double bevel, of course, but single bevels are often a hot favourite with Eastern chefs, in particular, for sushi and sashimi preparation.
We all wear down over time with use and so do knife blades
The toughness and hardness of your blade will also affect how your blade wears over time when being sharpened at home in a non-professional way.
Most knives that are honed and sharpened on normal home-based steels, tend to change their shape over time - and, under close inspection, the edges of your knife can end up looking more like a bow shape than the straight strong blade that it once was.
Re-bevelling is probably a good thing to consider in this instance - even more so than attempting to thin your blade. It may just be damaged.
A straight and sharp knife will cut better, regardless, and you may find that the problems you are having with your blade relate more to its shape and its edge than its thinness.
An expert opinion can help you here.
Do you really need to thin?
An indication that you might need to thin your knife, is if it tends to split your food rather than cutting through it. (Cleavers are the exception here, of course). Not only is splitting your food frustrating, it can also be dangerous – but like I have said, check the edge retention of your blade first. It may be a simpler fix.
Overall, if your knife is frustrating you, the best thing you can do is to seek out an expert opinion.
It may well be that the prime solution is to give your knife to your neighbour to cut their dog’s food with, and start again with a knife that is more suited to your needs.