In this sequence Jud tightly packs the finely polished parts of a finished lock into a rugged steel box containing bone charcoal and buries the box in the middle of the lit forge, slowly bringing up the temperature to 1550 degrees F.
After the box and its contents reaches the correct heat, the parts are heat soaked for about 2 hours. At the end of this time, the entire contents of the box is dumped quickly into water. Surface hardening of the mild steel has now occurred and the polished surfaces have taken on beautiful oxidation colors as shown in the final picture.