When the layer got thick, i.e continuous oxidation because of dry air in the surrounding, cuprous oxide will convert into cupric oxide. This oxide will be black in color. This is the chemical reason behind the black color formation of copper.,
Oxidized forms of manganese usually remain dissolved in water, giving it a black tint. These abrupt changes in the chemical forms of iron and manganese are responsible for the staining properties of aquifer waters containing high concentrations of these elements.Aug 23, 2019
This green oxide is non conductive. However the copper wire that is crimped by the terminal connection or covered by insulation are protected from this mild acid mixture and thus stays copper bright and totally conductive. I have seen gold, silver and iron turn black.
If you want to protect your copper while it is still new and shiny, clean any oil or other contaminants from the metal. This can be done by simply wiping the metal with a solvent cleaner like xylene or denatured alcohol which can be purchased at most hardware or paint stores.
The presence of oxidizing acids; heavy-metal salts, sulfur, and ammonia; and a number of sulfur and ammonia compounds can cause corrosion to set in. Water that comes from a well is much more likely to contain these materials and put copper lines in jeopardy—but it can occur in the civic water system as well.Feb 20, 2017
Definition of black copper 1 : melaconite. 2 : a product containing usually 70 to 99 percent of copper formed in smelting copper ores direct to metal without first forming matte or by remelting old or scrap copper and copper alloys.
When the layer got thick, i.e continuous oxidation because of dry air in the surrounding, cuprous oxide will convert into cupric oxide. This oxide will be black in color. This is the chemical reason behind the black color formation of copper.