Ritual wine vessel (zun)

Look closely at the surface patina of this Shang dynasty bronze vessel. The bronze surface slowly corroded while the vessel was buried in the ground (more than three thousand years). The long-burial corrosion process results in the gradual formation of layers of different substances depending upon the composition of the bronze, the amount of oxygen and humidity present, and other factors. The microscopic cross section of such a corroded bronze reveals the many layers of various colors, with the corrosion penetrating deep into the bronze. Modern fakes may look corroded on the surface, but when studied in cross section under the microscope the deep, irregular corrosion of an authentically old bronze is lacking.