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Similar processes can be found on some ancient Egyptian copper sheets. [3] Another example of early chemical coloring of metals is the Nebra sky disk, which has a green patina and gold inlays. An early example of black colored iron is the famous Celtic spearhead found in the River Thames and dated between 200 and 50 BC. [4] [5]
The Statue of Liberty, showing advanced patination; verdigris is responsible for the statue's iconic green colour.. Verdigris (/ ˈ v ɜːr d ɪ ɡ r iː (s)/) [1] is a common name for any of a variety of somewhat toxic [2] [3] [4] copper salts of acetic acid, which range in colour from green to a bluish-green depending on their chemical composition.
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. [4] Archaeologists 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. [1]
Its name comes from the natural pigments that form a patina on copper, bronze, and brass as it ages. [2] The most famous example is the green patina that formed on the Statue of Liberty in New York Harbor. In the Middle Ages, the patina was made by attaching copper strips to a wooden block with acetic acid, then burying the sealed block in dung ...
Copper is a good choice for gutters and downspouts because it makes strong leak-proof joints. Gutters and downspouts made with copper are expected to outlast other metal materials and plastics. Even in corrosion-prone seacoast environments or in areas with acid rain or smog, copper gutters and downspouts can provide 50 years or more of service ...
The metals and common colours of heraldry. One system of hatching is shown at right. Tinctures are the colours, metals, and furs used in heraldry.Nine tinctures are in common use: two metals, or (gold or yellow) and argent (silver or white); the colours gules (red), azure (blue), vert (green), sable (black), and purpure (purple); and the furs ermine, which represents the winter fur of a stoat ...
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Shakudō (赤銅) is a Japanese billon of gold and copper (typically 4–10% gold, 96–90% copper), one of the irogane class of colored metals, which can be treated to develop a black, or sometimes indigo, patina, resembling lacquer.