[Animats]

This is an issue with bronze statues. Washington, D.C. has many of them. The ones at Memorial Bridge are occasionally cleaned and polished, but most of the others are not and have turned green. New York City has some statues polished, some not, depending on who owns them. The Prometheus statue at Rockefeller Center and the Charging Bull at Bowling Green are kept shined up.

[bilekas]

Isn't the oxidation of the green sometimes part of the aesthetic though ?

[wil421]

I would’ve liked to have seen the Statue of Liberty in its original copper glory. The green has certainly become iconic but I’m sure the copper brown color was a sight to see.

[Animats]

There's monel metal, which has copper and nickel. That resists corrosion and remains a smooth dull brown for at least a century. There were some monel metal sculptures in the art deco era, but it never caught on.

Stainless steel is an option. That lasts, and you can pressure wash it. There's some nice Art Deco stainless work from the 1930s, most notably at the Chrysler Building. But it's too shiny for most artistic uses.