Aluminum

Aluminum is a lightweight, corrosion-resistant metal that became commercially available for construction in the twentieth century once electrolytic refining made it affordable, prized in architecture for a strength-to-weight ratio far better than steel and for the thin, naturally oxide-protected skin that shields it from further corrosion without painting. Its malleability allows extrusion into precise structural and glazing profiles, which made it the material of choice for curtain-wall framing, window systems and roofing from the mid-twentieth century onward, and its reflectivity and ability to be anodized in a range of colors have also made it a common cladding and decorative material on modernist and contemporary buildings.