brass or bronze, will weather differently from 'pure' copper cladding. Natural copper patina at the Nordic Embassies (Berlin) įacade cladding ( copper cladding copper wall cladding) with alloys of copper, e.g.

Buildings in damp coastal/marine environments will develop patina layers faster than ones in dry inland areas. Ī patina layer takes many years to develop under natural weathering. In industrial and urban air environments containing sulfurous acid rain from coal-fired power plants or industrial processes, the final patina is primarily composed of sulphide or sulphate compounds. In clean air rural environments, the patina is created by the slow chemical reaction of copper with carbon dioxide and water, producing a basic copper carbonate. The green patina that forms naturally on copper and bronze, sometimes called verdigris, usually consists of varying mixtures of copper chlorides, sulfides, sulfates and carbonates, depending upon environmental conditions such as sulfur-containing acid rain. See also: Copper in architecture § Natural patinas The Statue of Liberty gets its famous green color from the natural patina formed on its copper surface. The chemical process by which a patina forms or is deliberately induced is called patination, and a work of art coated by a patina is said to be patinated.Ĭopper weather vane with verdigris patina Acquired patina Figuratively, patina can refer to any fading, darkening, or other signs of age, which are felt to be natural or unavoidable (or both). The word patina comes from the Italian patina (shallow layer of deposit on a surface), derived from the Latin patĭna (pan, shallow dish). It also refers to development as the result of weathering of a case-hardened layer, called cortex by geologists, within the surface of either a flint or chert nodule. In geology and geomorphology, the term patina is used to refer to discolored film or thin outer layer produced either on or within the surface of a rock or other material by either the development of a weathering rind within the surface of a rock, the formation of desert varnish on the surface of a rock, or combination of both. This has led stone tool analysts in recent times to generally prefer the term cortification as a better term to describe the process than patination. Īrchaeologists also use the term patina to refer to a corticated layer that develops over time that is due to a range of complex factors on flint tools and ancient stone monuments. Patina also refers to accumulated changes in surface texture and color that result from normal use of an object such as a coin or a piece of furniture over time. In common parlance, weathering rust on steel is often mistakenly referred to as patina. On metal, patina is a coating of various chemical compounds such as oxides, carbonates, sulfides, or sulfates formed on the surface during exposure to atmospheric elements ( oxygen, rain, acid rain, carbon dioxide, sulfur-bearing compounds). They may also be aesthetically appealing. Patinas can provide a protective covering to materials that would otherwise be damaged by corrosion or weathering. The patinas on leather goods are unique to the type of leather, frequency of use, and exposure. Patina ( / p ə ˈ t iː n ə/ or / ˈ p æ t ɪ n ə/) 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 and wooden furniture (sheen produced by age, wear, and polishing), or any similar acquired change of a surface through age and exposure.Īdditionally, the term is used to describe the aging of high-quality leather. The external layer has been weathered by moisture and rain, leading to the oxidation of copper.

Pre-colonial copper coin formerly used in the Copper Belt ( Democratic Republic of the Congo and Zambia). 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. Copper roof on the Minneapolis City Hall, coated with patina The Dresden Frauenkirche. For the United States Navy ship, see USS Pattina (SP-675).

Aluminium bronze patina