i mean cor ten steel( rusted)
Bill summed it up pretty quick and provided a link. For some reason you are focusing on the copper content when it really is insignificant in the overall picture of the sun hitting its surface. If you could elaborate more, maybe we could offer a better answer.
If the steel is true Cor Ten steel, it does not require waxing. Cor Ten is a steel designed to rust slowly over time ... then the rust acts as a natural barrier to prevent further rust. Check out the United States Steel building in downtown Pittsburgh, PA ... its nickname is The Rusty Nail.
