The slag in wrought iron also provides natural corrosion resistance. Nearly all ferrous metals rust, but wrought iron does a better job at handling it. As corrosion progresses, the fibers tend to disperse the rust into an even film, which gives the metal a natural brownish appearance. This film repels the scattering spotty corrosive attack that other metals endure.

Because of its corrosion resistance, wrought was the metal of choice in earlier years for marine use, bridges, and girders. In fact, in extremely corrosive areas, an architect may still specify the metal. Another niche where wrought is still alive and well is in the craft of knifemaking.