Patina
Definition: Patina refers to the surface layer that forms on materials such as metal, wood, or paper as a result of aging, handling, or environmental exposure. In fine art and antiques, patina is often prized as a sign of authenticity, history, and aesthetic richness.
In sculpture, especially bronze, patina can be intentionally applied through chemical treatments or develop naturally over time. On prints and works on paper, toning and surface wear may also be referred to as patina when visually desirable.