City of Loveland

Wikipedia: Weathering steel, best-known under the trademark COR-TEN steel and sometimes written without the hyphen as corten steel, is a group of steel alloys which were developed to eliminate the need for painting, and form a stable rust-like appearance if exposed to the weather for several years. The name is short for “corrosion resistance” and “tensile strength”.
In other words, the steel is allowed to rust in order to form the protective coating.
Product Lines: Custom Series, Exterior Signage
Type of Sign: Dimensional Letters, Dimensional Sign Creations, Post & Panel Signs
Type of Facility: Government