Alcohol, or spirit, lamps and annealers were used to heat small balls of “crinkled” gold foil, causing impurities coating the gold to melt away. Removing the impurities allowed these individual pellets of gold foil to adhere to each other when forcefully compressed into a filling cavity.
Shown here are several heating devices, and other material, used by dentists when practicing the gold foil technique, including gold as foil, pellets, cylinders, and sponge or “crystal,” automatic gold foil condensers, alcohol lamps and an annealer, as well as a student and an instructional model gold foil preparation.
Glenner, RA 1994 How it evolved: Gold fillings. Bull Hist Dent 42(3):129-130, November.