Sets furnace controls to regulate flow of air, gas, oil, or current to heat metal to specified temperature. Observes color, fluidity of molten bath, and appearance of metal on bar, to estimate temperature, or measures temperature, using pyrometer.
Inserts end of green pole into furnace to prevent oxidation of copper.
Adds reagents to remove impurities, according to type of metal processed. Skims slag with rabble, dross hoe, or ladle. Opens blowers to force air through tuyeres to agitate bath, and stirs bath with wooden pole or iron rod to release oxygen. Seals taphole with fire clay and firebrick. Sprays dore or silver crystals with water, and dries them with vacuum drier prior to melting.