The selection of metal fundamentally determines an outdoor sculpture's ability to withstand environmental challenges. Bronze develops a protective patina over time, making it ideal for long-term installations, though this greenish oxidation alters its original appearance. Stainless steel's chromium content creates an invisible oxide layer that resists corrosion exceptionally well, maintaining its sleek finish for decades with minimal maintenance.

Copper offers striking visual transformations as it weathers, transitioning from bright orange to rich verdigris, but requires structural considerations as it softens slightly over time. Cast iron provides affordability and vintage charm, yet demands frequent sealing to prevent destructive rust penetration. Modern corten steel intentionally forms a stable rust layer, eliminating maintenance while creating distinctive earthy tones.

Each metal responds uniquely to UV exposure, acid rain, and temperature fluctuations. Marine environments accelerate corrosion, making aluminum or specially coated metals preferable for coastal installations. Proper fabrication techniques—like adequate thickness and drainage holes—can triple a sculpture's lifespan regardless of material. Regular cleaning (frequency varying by metal type) prevents accelerated degradation from pollutant accumulation.

Artists must balance aesthetic goals with practical durability, often combining metals—such as bronze figures on stainless steel bases—to optimize both visual impact and structural integrity. Understanding these material behaviors ensures outdoor sculptures remain enduring landmarks rather than temporary installations.