Reading the heat
Learn the heat colors so you always know when to strike.
The color is the temperature
Steel doesn't come with a readout. It comes with a glow, and every smith reads that glow the way a cook reads a steak. The colors run from a faint red at 500°C to a blinding white at 1200°C.
The scale that matters
black heat 20–300°C too cold to move, don't bother faint red 500°C just starting to be plastic cherry red 815°C the sweet spot for forging bright red 900°C moves easy, watch the grain orange 980°C weld heat approaches yellow 1100°C danger — the steel is burning
The critical number
723°C is the austenite transformation — below it the steel won't fully re-form its crystal structure. Learn to land just above it, and you'll move metal cleanly without burning carbon out of the edge.