The protective patina layer cannot form, however, if the surface of the steel is continuously damp or dirty. • Surfaces of weathering steel can be painted using the same methods applied in ordinary steels. As a result of the special alloying of the steel, a coating may last twice as long as a coating on ordinary steel. If Cor-Ten steel is continuously exposed to water, it is generally recommended to be painted. Nonetheless, the painting process requires the steel surface to be completely free of oxide through preferably mechanical abrasion. • Imposed weight on building structure must be considered.