Weathering steel, often referred to by the genericized trademark COR-TEN steel, is a group of steel alloys which were developed to eliminate the need for painting, and form a stable rust-like appearance after exposure to weather. COR-TEN has successfully overcome rust, steel’s most weakest, by capitalizing on its unique “rust cures rust” function. When exposed to the atmosphere without painting, COR-TEN begins to rust in the same way as ordinary steel. But soon the alloying elements in COR-TEN cause a protective surface layer of fine-textured rust to form, thereby suppressing corrosion rate.