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These include the formation of a black incrustation or a white powdery substance (mineral deposits) that has the potential to obscure the natural blue-green patina, or artificially applied patinas. Pollution-formed crusts could cause the metal to deteriorate and form small pits in the metal if not removed.
Bronze disease is an irreversible and nearly inexorable corrosion process that occurs when chlorides come into contact with bronze or other copper-bearing alloys. [1] It can occur as both a dark green coating, or as a much lighter whitish fuzzy or furry green coating. [1]
Tarnish is a chemical reaction on the surface of metal (copper, brass, silver, etc.) and causes a layer of corrosion. In the case of silver tarnish, the silver combines with sulfur and forms silver sulfide (Ag 2 S), which is black. The original silver surface can be restored if the layer of silver sulfide is removed. [4]
Iron and copper oxides can penetrate deep into the pores of ceramics and stones and create reddish-brown to black stains (iron oxide) and blue-green stains (copper oxides). The use of EDTA salt solution can be used to remove the oxides. A mild solution consists of 3% to 5% of EDTA; 15% to 20% solution in water on ceramics to remove the stains.
Pickling is a metal surface treatment used to remove impurities, such as stains, inorganic contaminants, and rust or scale from ferrous metals, copper, precious metals and aluminium alloys. [1] A solution called pickle liquor , which usually contains acid , is used to remove the surface impurities.
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This can be used for pet stains and out of doors. [3] There is no chief underlying chemical reason why club soda would be superior to plain water in stain removal. [8] Glycerine This can be used to soften "set" stains, especially on wool and non-water-washable fabrics. [3] Boiling water This can be used to take out fruit juice stains.
It can be used on copper and its alloys, silver, nickel, iron, gold. The color depends on the duration of immersion, the sequence of colors on brass: Golden yellow-copper-purple-dark, blue-light, blue-chrome-nickel-red-grey, blue, and gray-black to iron or carbon steel. [34]