Hard steel is brittle steel. To prevent the tool from snapping during use, the smith performs a final . By gently reheating the metal to a much lower temperature (often judged by the "straw" or "blue" oxidation colors on the surface), the smith restores just enough elasticity to make the blade or tool durable for a lifetime of service.
Once the metal reaches its "critical temperature"—glowing a vibrant cherry red or a searing lemon yellow—the clock starts ticking. The smith has only seconds to work before the steel loses its plasticity. At the Blacksmith's Hand, Pt. 2
These tools smooth out hammer marks, creating the crisp lines and professional finish that distinguish a master’s work from a novice’s. The Trial by Fire: Quenching Hard steel is brittle steel