《天工开物·中篇·锤锻》
要先用经过淬火的硬钢小凿，在锉坯的表面上开出成排的纵纹及斜纹，并且凿的时候要自倾斜的方向下刀，出来的纹沟才能有火焰般的锋芒。
以已健钢钅斩划成纵斜文理，划时斜向入，则文方成焰。
First, use a small piece of hardened hard steel chisel to open a row of vertical and diagonal patterns on the surface of the blank. When chiseling, you must cut from the inclined direction to make the grooves out to have a flame-like sharpness.