Verdigris

Verdigris ( ) is a common name for any of a variety of somewhat toxic copper salts of acetic acid, which range in colour from green to a bluish-green depending on their chemical composition. Once used as a medicine and pharmaceutical preparation, verdigris occurs naturally, creating a patina on copper, bronze, and brass, and is the main component of a historic green pigment used for artistic purposes from antiquity until the late 20th century, including in easel painting, polychromatic sculptures, and illumination of maps. However, due to its instability, its popularity declined as other green pigments became readily available. The instability of its appearance stems from its hydration level and basicity, which change as the pigment interacts with other materials over time.

Verdigris ( ) is a common name for any of a variety of somewhat toxic copper salts of acetic acid, which range in colour from green to a bluish-green depending on their chemical composition. Once used as a medicine and pharmaceutical preparation, verdigris occurs naturally, creating a patina on copper, bronze, and brass, and is the main component of a historic green pigment used for artistic purposes from antiquity until the late 20th century, including in easel painting, polychromatic sculptures, and illumination of maps. However, due to its instability, its popularity declined as other green pigments became readily available. The instability of its appearance stems from its hydration level and basicity, which change as the pigment interacts with other materials over time.

Uses

Verdigris is a naturally occurring protective layer on metals such as copper, brass, and bronze. In addition to being a desirable artistic effect, it has been used primarily as a pigment and in now-outdated medicinal preparations. When burned, verdigris produces a green flame.

Pigment

Verdigris has been used as a pigment since antiquity, including in paintings in Rome and Pompeii. The use of verdigris continued into the Middle Ages, Renaissance and Baroque paintings. It has been identified in The Last Supper (1306) by Giotto. During the 15th and 16th centuries, it was used in paintings for its transparency and brilliance. It was difficult to create strong green colors in paintings due to the limitations of the existing green, yellow and blue pigments. In early Italian, Netherlandish, and German paintings, verdigris was widely used to create pure green tones for landscapes and drapery, such as the green coat of Saint John in the Mond Crucifixion by Raphael. Verdigris was used as both glaze and opaque paint. When verdigris glaze was combined with lead white or lead-tin yellow, it created a deeply saturated green. It was used in oil-based house paint for French and Dutch country houses. Verdigris also was used as an imitation of 'Chinese varnish' on European lacquer. However, during the 19th century, the use of verdigris began to decrease as alternatives such as Emerald Green and viridian became more popular.

Medicine

Verdigris has also been used in medicine, and is identified in the Pharmacologia of John Ayrton Paris as the healing rust of the Spear of Telephus mentioned by Homer. Verdigris solids were also used for pharmaceutical preparations in the 18th century to treat canker sores.

See also

Bronze disease Green pigments List of colors List of inorganic pigments Patina

References

External links

National Pollutant Inventory – Copper and compounds fact sheet Verdigris, ColourLex Making Pigments – Verdigris, Paul Grosse

Text derived from https://en.wikipedia.org/w/index.php?oldid=1340422176 under CC BY-SA 4.0; modifications have been made.