Page 248 - Copper and Bronze in Art: Corrosion, Colorants, Getty Museum Conservation, By David Scott

Pourbaix diagram for the
F I G U R E 6. 1 Cu-S-H 2 0 system (Schweizer 1994) .

Schweizer concluded that after the Bronze Age lake dwellers finished using these objects,
the bronzes were discarded in damp, waterlogged soil or were thrown into the lake close to the
shore and sank to the bottom. There they remained for a considerable period of time in anaero­
bic conditions. Later the water level in the lake dropped, exposing some of the objects to oxidiz­
ing conditions, and the sulfides transformed into basic carbonates and basic sulfates. The lake
level rose around 750 B.C.E. and submerged all of the objects again, probably initiating further
slow corrosion of the material.

C O P P E R S U L F I D E S
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