Patina

Copper roof on the Minneapolis City Hall, coated with patina
The Dresden Frauenkirche. The church was destroyed during the bombing of Dresden in 1945 and then rebuilt from 1993 to 2005 with new material; the stones with the black patina are the parts that survived the firebombing from the original 18th-century church.
Pre-colonial copper coin formerly used in the Copper Belt (Democratic Republic of the Congo and Zambia). The external layer has been weathered by moisture and rain, leading to the oxidation of copper.

Patina (/pəˈtnə/ pə-TEE-nə or /ˈpætɪnə/ PAT-ih-nə) is a thin layer that variously forms on the surface of copper, brass, bronze, and similar metals and metal alloys (tarnish produced by oxidation or other chemical processes), or certain stones[1] and wooden furniture (sheen produced by age, wear, and polishing), or any similar acquired change of a surface through age and exposure.

Additionally, the term is used to describe the aging of high-quality leather. The patinas on leather goods are unique to the type of leather, frequency of use, and exposure.

Patinas can provide a protective covering to materials that would otherwise be damaged by corrosion or weathering. They may also be aesthetically appealing.

  1. ^ European Geosciences Union. General Assembly; Přikryl, Richard; Smith, Bernard J.; Geological Society of London (2007). Building Stone Decay: From Diagnosis to Conservation. Geological Society. pp. 295–. ISBN 978-1-86239-218-2. Retrieved 26 September 2012.