Why is the Statue of Liberty green?

Why is The Statue of Liberty Green?

Why Is The Statue Of Liberty Green? Discover why the Statue of Liberty has been green and conduct a simple experiment to demonstrate the simple chemical process. Keep reading!

Why is the Statue of Liberty green?
Why is the Statue of Liberty green?

Why is the Statue of Liberty green?

What materials make up the Statue of Liberty?

What materials make up the Statue of Liberty?

The Statue of Liberty is constructed of an iron frame with a sheet of pure copper draped over it. Because the torch flame is coated in gold leaf rather than copper, it is extremely bright. However, it wasn’t always this way—the flame was originally copper-plated as well. 

Gutzon Borglum, who also created Mount Rushmore, was commissioned to work on the statue’s 1916 renovations. He removed a large portion of the torch’s copper surface and added glass windows in its place. 

Snow and rain dripped in through the windows, accelerating corrosion. Due to excessive damage, the old torch was removed and placed in the monument’s museum in the mid-1980s (the statue’s 100th birthday). The gold leaf has been applied to the replacement torch.

Chemical Reactions Cause the Statue of Liberty to Turn Green

Most people are aware that verdigris is formed when copper reacts with air, but the Statue of Liberty has its own distinct color due to its unique environmental conditions. 

As you might expect, producing green oxide is not as simple as combining copper and oxygen. The copper oxide keeps reacting, producing copper sulfate, copper sulfide, and copper carbonates.

The blue-green patina is composed of three main compounds:

  • Green: Cu4SO4(OH)6
  • Green: Cu2CO3(OH)2 
  • Blue: Cu3(CO3)2(OH)2 

This is what happens: Initially, copper undergoes an oxidation-reduction as well as redox reaction with oxygen from the air. When oxygen receives electrons from copper, the oxygen is reduced and the copper is oxidized.

  • Pink/ Red: 2Cu + O2 → Cu2O 

Following that, the copper(I) oxide keeps on reacting with oxygen to produce copper oxide (CuO):

  • Black: 2Cu2O + O2 → 4CuO

Sulfur from air pollution brought on by coal burning was present in large amounts when the Statue of Liberty was constructed:

  • Black: Cu + S → 4CuS

CuS reacts with air carbon dioxide (CO2) and water vapor hydroxide ions (OH-) to form 3 compounds:

  • Green: 2CuO + CO2 + H2O → Cu2CO3(OH)2
  • Blue: 3CuO + 2CO2 + H2O → Cu3(CO3)2(OH)2 
  • Green: 4CuO + SO3 +3H2O → Cu4SO4(OH)6

In the case of the Statue of Liberty, the speed at which the patina develops over the course of 20 years—and not just because oxygen and carbon dioxide are present—depends on the humidity and air pollution. Patina evolves and develops over time. Since almost all of the Statue’s copper is still its original composition, the verdigris has been growing for more than 130 years.

Why do architects employ patina?

Why do architects employ patina?
Why do architects employ patina?

Occasionally, when the projects are installed, architects ask for a specific patina color. Chemically induced pre-patination systems that are applied in the factory can produce a variety of colored finishes that resemble natural patination. 

When making repairs, pre-patinated copper comes in particularly handy if you need to provide close color matches to vintage copper roofs.

Do you know what is Statue of Liberty meaning?

Simple Penny Patina Experiment

You can reproduce the patina of the Statue of Liberty. The time it takes to see results isn’t even 20 years.


  • pennies made of copper 
  • vinegar (dilute acetic acid)
  • salt (sodium chloride)


  1. In a small bowl, combine one teaspoon of salt and fifty milliliters of vinegar. The precise measurements are unimportant.
  2. Incorporate the mixture into the coin’s lower half or another copper-based object. Examine the outcomes. If the coin was dull before, the dipped half ought to now be shiny.
  3. Allow the coin to sit in the liquid for 5-10 minutes. The vinegar’s acetic acid and sodium chloride (salt) interacted to create sodium acetate and hydrogen chloride (hydrochloric acid). The acid dissolved the previous oxide layer. This is possibly how the statue looked when it was first built.
  4. Chemical reactions continue to occur. The salt and vinegar coin should not be rinsed. Allow it to dry naturally and check it the next day. Verdigris is being created by a reaction between the copper and the water and oxygen vapor in the air.

Is it possible to paint the Statue of Liberty?

Is it possible to paint the Statue of Liberty?

Authorities decided that the Statue needed to be painted when it first started to turn green. In 1906, stories about the project appeared in New York newspapers, causing a public outcry. When asked if the statue should be painted again, a Times reporter spoke with a copper and bronze manufacturer. According to the company’s vice president, painting is unnecessary because the patina protects the metal, and such an act could be considered vandalism.

There have been numerous suggestions over the years to paint the Statue of Liberty, but nothing has come of it. But following a renovation to put in windows, the torch, which was initially made of copper, corroded.

Explore more: Statue of Liberty Poem

How long did it take for the Statue of Liberty to turn green?

The statue’s initial construction left it with a dull brown hue that reflected the copper plates’ original state. But gradually over the following 30 years, it changed to the present-day shade of green.

Do you know how old is Statue of Liberty?

Frequently Asked Question

Did they know the Statue of Liberty would turn green?

He knew it would turn green-blue as he was constructing the statue out of copper sheets. Copper was a good choice for the monument, though, because of a number of factors, including this one.

Why don’t they clean the Statue of Liberty?

The patina protects the statue from the harsh elements of New York Harbor, such as high winds, salt water, and pollution. In a statement to AM New York, National Park Service spokesman Jerry Willis said that cleaning the Statue of Liberty’s green patina might be more detrimental than beneficial.

Why did they build the Statue of Liberty out of copper?

Copper was significantly less expensive than precious metals (such as gold or silver) and significantly less expensive than stainless steel.

Now you know Why Is The Statue Of Liberty Green and how to make a small experiment about it. What do you think about the Statue of Liberty being blue? Please comment to share your thoughts with Artseensoho.

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