Grinding of knife blades

Blade Grinding and Blade Geometry

By applying different ways of grinding, various blade geometries can be produced:

Hollow grind

In this budget-friendly grinding technique, only the lower portion of the steel blank is ground. This method is commonly used for producing very low-end knives, but it's also typical for creating serrated edges.

PROS

Inexpensive

CONS

Thick blade above grinding area = high cutting resistance

A lot of cutting drag in area of concave edge

Thin and fragile blade on cutting edge

Graphic drawing showing geometry of a hollow grind knife blade in a cross section

Flat grind

The blade is ground flat on both sides to a thin edge.

PROS

Thin blade and potentially good sharpness

CONS

Thin and fragile edge

Contact of food along the entire blade = sticking and drag; more power needed for cutting

Graphic drawing showing geometry of a flat grind knife blade in a cross section

Convex grind

The blade is ground on both sides with a convex geometry. Common way of grinding German style knives.

PROS

Food contact only on small area of blade = less sticking and drag

CONS

Thicker blade in area close to edge = less sharpness

Graphic drawing showing geometry of a convex grind knife blade in a cross section

Graphic drawing showing geometry of a single bevel hollow grind knife blade in a cross section

Graphic drawing showing geometry of a Japanese grind flat convex combination thin grind knife blade in a cross section

Single bevel flat grind

Adding a flat bevel to just one side of the blade. While it's a standard technique for scissors, it's uncommon for quality knives. However, you’ll often find this type of grinding on lower-cost imitations of traditional Japanese knives.

PROS

Very inexpensive way of blade grinding

CONS

Blade only works for either left- or right-handed people, not for both

Straight cuts are difficult

Single bevel hollow grind

Hollow grind on one side of the blade, paired with a bevel on the opposite side. It’s the signature grinding technique used for traditional Japanese single-bevel knives.

PROS

Very thin edge and hence very high sharpness

Generally good stability of blade

CONS

Blade only works for either left- or right-handed people, not for both

Straight cuts are difficult (which is intended for a very specific use)

Thin and hence fragile and sensitive edge

Hybrid grind

Almost flat grind on the upper part of the blade, with a convex grind in the lower third. It’s the hallmark of Japanese double-bevel knives, combining strength and sharpness.

PROS

Generally thin blade, with added stability in edge area

Best compromise between sharpness and blade/edge stability

Less sticking/drag

CONS

More expensive, since more grinding steps