I was just reading about the Statue in Mental Floss and had a few unanswered questions.
First, how long was the State actually copper-colored? When did it start to change? When did it become completely green?
Second, what did people think of this at the time? I assume the sculptor knew it would happen, but did the average New Yorker, or New York newspaper editor, knew that the landmark they loved was going to change color?
Finally, is there any way to change it back? Could the copper be painted to look like copper? Would people want to do this or are they used to the green?
It took around 6 years according to Wiki and the link in it.
Here’s a quote “The layers on the statue are not corrosion; it is a thin protective layer that covers the surface of exposed copper known as a patina. This green patina began gradually covering the surface of Miss Liberty just after 1900, and was noted in the press at least as early 1902. By 1906, the goddess of liberty was entirely green.”
It is possible to treat at least small surfaces. The sculpture on the Ottawa War Memorial used to be the same green, as shown here.
However, about a decade ago they cleaned off the verdigris and appear to have coated it with something, so it is now a dark brown, without any sign of verdigris starting, as shown here.
Dunno if you could do that with something as big as the Statue.
I make copper bowls. Copper is usually supplied “bright” which is polished and with a protective plastic sheet stuck to the surfaces. However it can be supplied with a patina (usually if its being used a roof sheets as any working will scrape it off) bright copper remains bright for a very short time dulling visibly in a day or so, even in clean air, a city’s air would cause this quicker.
Sulfur and acids in the air reacts with copper causing it to go green. Speeding that up is fairly easy, commercial patina solutions work well, with green or dull brown being available, however i found that liquid plant food turns it green (it has sulfur in its make up) and Ferric chloride (use for etching circuit boards) turns it black/brown. Salt spray will also speed it up but generally its a bit hit and miss !
Patina-ed Copper can be easily cleaned back to bright using a dilute acid like vinegar or lemon juice. Preserving the bright finish is a question of coating with a clear and impervious coating like varnish or lacquer.
1886 to 1906 is 20 years, not 6. Although parts of the statue were built in 1876, so 30 years total.
And by the way, historical records are the only way to answer this question, because you can’t generalize the time it takes copper to develop a patina. It’s entirely dependent on the environment.
Statues are more usually made of Bronze which is easier to cast, bronze is most usually treated with a patina solution that sends it a deep brown. Left to its own devices it will go green as it is heavy in copper. The brown patina is more durable than the green,which is powdery and tends to flake off as it accumulates.
If you see that chart - then it looks pretty green after the first 5-7 years. But you are right that it gets the total light green color in 25-30 years. So unless the statue was initially cleaned for the initial years, it would have taken that time to get totally green.
The Statue of Liberty was cleaned down to bare copper in 1985-1986. It looked green again within the year. It may have appeared more coppery right up close, but from the NYC pier and NJ’s Liberty Park it was green.
In other words, rust is different because it flakes away from the underlying surface, not only making it ugly but exposing uncorroded material and allowing the entire iron object to be rusted to nothing. A copper patina stays smooth, doesn’t flake off and acts as a protective layer.
There ar two major buildings at the University of Wyoming which are roofed with copper. the Art Museum and the Arena Auditorium. Both turned very black within a few months of completion and have been that way since.
That’s incorrect. It was stripped bare only on the inside. The copper that was used to patch it came from the rooftop of Bell Labs, which had a similar patina to the statue. Here’s a picture of the SoL from the day it reopened, and it clearly maintained it’s patina.
I went to NYC for “Liberty Weekend”, as it was called, and didn’t recall it being all coppery, so I looked it up on Wikipedia.
The Statue of Liberty’s color is so much a part of its iconic image that people would probably hate it if they DID figure out a way to protect it from turning green.
