What is the deal with "patina"?

[Classic Bowties]

Originally Posted by 68gmsee

American Heritage dictionary college edition.

Patina: A thin layer of corrosion, usually brown or green, that appears on copper or copper alloys, such as bronze, as a result of natural or artificial oxidation. 2. The sheen produced by age and use on any antique surface.

Fairly simple to understand as quoted above out of the American Heritage dictionary : 2. The sheen produced by age and use on ANY antique surface.