Our copper finish post caps come with a thin, clear marine lacquer designed to protect them before and during installation. Once exposed to the elements, the sun's ultraviolet rays, moisture and pollution begin to break down this coating, exposing the metal underneath. In its natural state, copper breaks down in the elements and patinas. In general, copper progresses from a natural salmon color to a series of russet browns and grays, and finally to a blue-green or gray-green patina.