Bronze, iron, and steel sculptures age in distinct ways due to their material properties. Bronze develops a protective patina over time, a greenish or brownish layer caused by oxidation, which actually shields the metal underneath from further corrosion. This natural process enhances bronze sculptures' longevity, often preserving fine details for centuries.

In contrast, iron sculptures rust when exposed to moisture and oxygen, forming flaky, reddish-brown iron oxide that progressively eats away at the metal. Without protective coatings, iron sculptures can deteriorate significantly faster than bronze. Steel, while more resistant than iron, still suffers from rusting unless it's stainless steel or properly treated.

The aging process also affects aesthetics. Bronze's patina is often considered desirable, adding character and value, whereas iron's rust is typically viewed as deterioration. Modern conservation techniques can slow aging for all metals, but bronze's inherent durability makes it a preferred choice for outdoor sculptures meant to withstand the test of time.