Verdigris

Verdigris is the common name for the natural or artificially induced patina formed when copper, brass, or bronze is weathered and exposed to air or seawater over time. It is usually a bright bluish-green encrustation or coating.

Verdigris is a compound of copper carbonate and copper chloride, and it occurs naturally as the mineral malachite. The name 'verdigris' comes from the Middle English 'vert de Grece' (green of Greece), though the color is more on the bluish side of green.

Historically, verdigris was used as a pigment in paints, and was one of the most vibrant green pigments available. However, it was unstable and could fade or darken over time, and its corrosive effect on copper made it a somewhat problematic pigment. Over time, it was largely replaced by more stable and light-fast green pigments.

Despite these downsides, verdigris has an important place in art history. The Statue of Liberty, for example, is made of copper and has turned green due to the verdigris patina that has formed on its surface. This patina acts as a protective layer and prevents further corrosion of the copper beneath.

In contemporary art and sculpture, verdigris effects can be artificially induced to give works a certain aesthetic or to mimic the passage of time. However, this is typically done using safer, modern materials that mimic the look of verdigris.

In terms of safety, it's important to note that verdigris is toxic if ingested or inhaled, and precautions should be taken when handling it.