Steel chain, copper spheres, light post Outdoor Exploratorium, Fort Mason. San Francisco CA, 2009
An old mooring chain found hanging on the seawall illustrates some of the counterintuitive phenomena that occur in the invisible electrochemical zones that govern corrosion rates along the shoreline.
Instead of deteriorating, as one would expect, the diameter of the steel chain links increase in size as they descend down into the intertidal region. A changing color gradient on a strand of copper spheres further illustrates distinct bands of electrochemical activity caused by the varied mixtures of salt, air, and water present at different phases of the tidal flux.