How the Statue of Liberty Became a Battery: Galvanic Corrosion

The Statue of Liberty began its majestic construction in 1876 in France and made her grand entrance to the United States between 1885 and 1886. At that time, France was still playing with “puddle iron” (wrought iron, for those keeping score), as modern steel production hadn’t hit its stride yet. As a result, the statue's internal frame was crafted from this readily available puddle iron with a thin skin of copper on top. 

Imagine this: the statue is essentially a large iron column wrapped in a delicate skin of copper, 300 sheets, to be exact, thus creating Lady Liberty’s iconic shape. However, things got tricky thanks to a little science called Galvanic Corrosion. This sneaky process occurs when dissimilar metals come into contact, triggering an electrochemical reaction. Throw in some moisture, and you've got the perfect recipe for accelerated deterioration. Thankfully, the ingenious designer Gustave Eiffel and architect Eugène Emmanuel Viollet-le-Duc put a stopgap in place by adding a layer of shellac-soaked asbestos to separate the two materials and prevent an electrical fiasco.

 But alas, time is a tricky adversary. That shellac barrier eventually flaked off, allowing moisture to get cozy in the asbestos layer and act as an electrolyte. This unfortunate cocktail led to the iron corroding at a rate 100 times faster than it should have. Why? Because iron acted like a sacrificial anode, causing it to rust, while copper, the noble cathode, remained blissfully intact. In short, our beloved statue had transformed into a colossal 0.25-volt battery!

 Now, you might wonder, how is this similar to your everyday car battery? Both utilize an electrolyte: your car's battery uses acid, while Lady Liberty has to contend with moist salt air, thereby sparking a galvanic cell between the dissimilar metals. A battery features an anode and a cathode; in this case, copper serves as the cathode, while the iron structure serves as the anode. These three elements are what you need to generate an electrical current. While this reaction is intentional in a car battery, it ultimately leads to its demise, hence the need for replacements every few years.