Sculptors have taken advantage of weathering steel's corrosion resistance, availability, fabricability, and appearance to create many striking and appealing works of art. The appearance of weathering steel in sculptures can be quite varied, even in the same work. In general, as weathering steel's rust film ages its appearance changes from a matte red-orange color typical of newly-rusted steel to darker colors ranging
from dark brown to blackish purple. This and other aspects of the appearance of weathering steel can be explained by an understanding of the intrinsic behavior of the steel in atmospheric corrosion, the morphology of the rust film, and environmental factors. This knowledge can be used to understand the dependence of the appearance of weathering steel in sculpture on its exposure history. Keywords: weathering steel, sculpture, atmospheric, specular, rust, color