A sharp knife has a small contact area, requiring minimal force to apply pressure and cut through food. In contrast, a dull knife has a larger contact area. To slice food, a cook must press harder and use more force.

According to Chef Vu Nhat Thong from Eric Cooking Class, using excessive force is a common cause of kitchen accidents. When straining to cut, users can easily lose control of the knife's direction. When handling ingredients with curved and slippery surfaces, such as onions or tomatoes, a dull blade often fails to cut into the food and instead slips, moving towards the hand holding the ingredient.

From a medical perspective, wounds caused by dull knives are often more severe. The University of Rochester Medical Center (URMC, US) states that because dull knives require significant pressure to cut, when they slip, they carry strong momentum, resulting in deep wounds.

A sharp blade creates a clean cut, causing less damage to surrounding tissue and promoting faster healing. Conversely, a dull knife tends to tear and crush tissue. These jagged wounds make suturing difficult and are more likely to leave scars.

To check the condition of a knife, users can hold an A4 sheet of paper upright and gently slice downwards with the knife. If the knife glides through easily, creating a straight cut, the blade is sharp. If the knife tears, crumples the paper, or fails to cut, it needs maintenance.

When maintaining knives, it is important to distinguish between honing and sharpening. A honing steel does not sharpen the blade but merely realigns the metal edge that may have bent. This should be done frequently before cooking.

Sharpening, on the other hand, involves removing a layer of metal to create a new cutting edge. This process only needs to be performed every few months, depending on usage frequency.

Bao Nhien