patina

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patina

(păt`ənə), coating of carbonate of copper on articles of copper or bronze, formed after long exposure to a moist atmosphere or burial in the earth. Although commonly green, patina varies in color and consistency; it may be red, brown, black, blue, or gray, or it may be smooth, glossy, or crusty. It may be imitated by a number of oxidation processes. The term has been extended to include the film formed on metals, pottery, marble, and other materials by exposure and to the mellow surface acquired by furniture with time and waxing.

Patina

A greenish-brown crust produced by oxidation that forms on the surface of copper and bronze, often multicolored and considered decorative; any thin oxide film which forms on a metal or other material.

Patina

 

a film ranging from green to cinnamon in color that forms on the surface of copper, bronze, and brass articles. A patina results from the natural corrosion of the metal or from patination—that is, heating or processing with oxidizing agents. A patina formed by the latter method is used to protect works of art and for decorative purposes. Roman artists were the first to recognize patina as a sign of beauty through aging. The term “patination” is also used to designate the process whereby articles not made from copper alloys, for example, plaster-of-paris sculptures, are tinted bronze.

patina

[′pat·ən·ə or pə′tē·nə]
(geology)
A thin, colored film produced on a rock surface by weathering.
(metallurgy)
The greenish product, usually basic copper sulfate, formed on copper and copper-rich alloys as a result of prolonged atmospheric corrosion.

patina, patination

1. A greenish brown crust which forms on bronze.
2. Any thin oxide film which forms on a metal; often multicolored.
3. A film, similar in color, which forms on a material other than metal.
4. Such effects artificially induced, or imitated.
5. A green coating on the surface of copper or copper alloys that have been exposed to the atmosphere for a long time.

patina

1
a film of oxide formed on the surface of a metal, esp the green oxidation of bronze or copper

patina

2
a broad shallow dish used in ancient Rome
References in periodicals archive ?
The most traditional colors for bronze patina are in the brown, black, blue, and gray-green families.
However, sections of the patina itselfmay be changing.
X-ray diffraction studies show thatthe green patina consists largely of two basic copper sulfates: brochantite, CuSO.
As a result, this antlerite-loaded green patina may be washing away, especially in areas exposed to the prevailing winds.
One of the interesting effects we saw was that in darkening areas, the green patina had a high antlerite content.
This finding and other patina analysesin recent years suggest that the copper of the Statue of Liberty may be suffering, or will suffer, atmospheric corrosion at higher rates than was the situation one or two generations ago," says Nielsen.
In contrast, the patina on a sample removedfrom the torch in 1905 and stored at the National Archives in Washington, D.
A more stable patina forms on the purer copper, he says, "which explains why the panel on the left side of the torch arm has retained its green appearance.
Graedel have been looking closely at the chemistry of patina formation.
By knowing something about the atmosphere and something about the analyses on all these pieces of copper, we've made what I think is the first decent, extensive coupling of the atmosphere in which the patina has grown to the chemical characteristics that we find on the patina.
With a better idea of which factors affectthe rate of patina formation, Graedel and Franey conclude that "the time required for the green patina to form has decreased from about 20 years in the late 19th century to about eight years today.