To get the right thickness requires a very sharp knife, and learning how to properly sharpen a knife was Wang Hsi-kun's first lesson: "Controlling your technique and pressure are paramount for grinding and sharpening a knife.
接著是「削牛皮」，削牛皮所用的刀必須夠鋒利，才能將牛皮削得厚薄恰到好處，如何磨出一把鋒利的刀，就是王錫坤的第一個課題。