Compared to plain steel, weathering steel contains a chemical composition that increases its resistance to atmospheric corrosion. Made to rust under the influence of weather, weathering steel develops a patina that acts as a protective layer to prevent corrosion of the steel. This material is suited for many applications in its unpainted condition. With time and consistent exposure to the elements, the weathering steel will go from a yellow-orange, to a deep rust orange color, to a dark brown.