Verdigris

Verdigris

Verdigris is a bluish-green patina formed on copper, brass, or bronze surfaces when exposed to air or seawater over time. This corrosion process occurs due to the reaction between the copper in the metal and atmospheric pollutants, such as sulfur dioxide and carbon dioxide, resulting in the formation of copper carbonate and other copper salts. The term verdigris is derived from the Old French vert-de-Grèce, which translates to green of Greece, likely referring to the widespread use of this pigment in ancient Greek art and architecture. Historically, verdigris was used as a pigment in paintings, particularly during the Renaissance period, prized for its vibrant, long-lasting color. However, its use declined due to its toxicity and the availability of safer, more stable green pigments. In architecture, verdigris is often seen on aged copper roofs, domes, and outdoor sculptures, where it develops naturally over time, creating a distinctive, weathered appearance that is often associated with historical buildings and monuments. The formation of verdigris can also be accelerated through chemical treatments, allowing artists and craftsmen to achieve the desired patina more quickly. While verdigris is a form of corrosion, it can actually protect the underlying metal from further deterioration by acting as a barrier against additional oxidation and weathering.

patina, oxidation, copper, pigment, corrosion

— John Armstrong