Cast Iron

Cast iron is an iron alloy with a high carbon content, poured molten into molds to form structural and decorative building components, strong in compression but brittle and comparatively weak in tension, which shaped how nineteenth-century engineers used it. Its ability to be cast into intricate, repeatable ornamental forms made it popular for columns, facades, balconies and storefronts, especially in mid-nineteenth-century American commercial buildings such as New York's SoHo cast-iron district, while its compressive strength suited it to columns and structural frames in early industrial buildings and greenhouses before structural steel, which handles tension far better, supplanted it for major load-bearing frames by the century's end.