And what is that faint green thing made up of? Any scientific reason?
No they don't, it is not paint. Some historic buildings have roofs covered with copper sheet rather than lead. Over several years the copper sheet acquires a fine coating of copper salts from the weather and these are pale green.
No they don't, it is not paint. Some historic buildings have roofs covered with copper sheet rather than lead. Over several years the copper sheet acquires a fine coating of copper salts from the weather and these are pale green.
