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Coin cleaning is the controversial process of removing undesirable substances from a coin's surface in order to make it more attractive to potential buyers. The subject is disputed among the numismatic community whether cleaning coins is necessary. Those that argue in favor of cleaning are also in dispute on which methods work best.
Production in the Old Copper Complex in Michigan and Wisconsin is dated between 6000 and 3000 BC. [8] [9] Natural bronze, a type of copper made from ores rich in silicon, arsenic, and (rarely) tin, came into general use in the Balkans around 5500 BC. Previously the only tool made of copper had been the awl, used for punching holes in leather ...
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]
Sealed, or lacquered, copper will present as much shinier than raw, or natural, copper—and it's also much easier to clean (tackle sealed copper with a warm, wet dishcloth and dish soap).
Metals with active corrosion fare better with lower relative humidity: copper or copper alloy objects up to 35% RH and iron objects 12–15% RH. Clean and well organized storage areas are important but materials in the environment are also considered. Wood and wood-based products (particle board, plywood) can off-gas and cause metals to ...
Renaissance Wax is also commonly used in the preservation of bronze and copper coins. The wax seals the coins and helps prevent deterioration from moisture and air exposure. It may [citation needed] also help prevent the onset of the chloride-related corrosion commonly called bronze disease, although it won't arrest this once started.