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Silver Corrosion

Last updated: May 4, 2017

What Does Silver Corrosion Mean?

Silver is a gray-white metal that is malleable and soft. The metal is found in lead ore, but can also be a byproduct of mining other metals like gold, copper and zinc. It is a precious metal classified alongside platinum and gold, and is the best conductor of electricity of all metals. The chemical symbol for silver is Ag.

Silver is known to be resistant to corrosion, as it does not oxidize easily. When silver is exposed to air, a layer of silver sulfide is formed on the surface.


Corrosionpedia Explains Silver Corrosion

When silver is attacked by sulfur, the chemical reaction leaves the metal with a brown-black patina which does not result in much metal loss. The attack also results in black fissures and pits. The rate of pitting attack is generally slow, but can increase if a stronger acid or salts are present. Salts catalyze the reaction, thus increasing the rate of attack. This is evident in salt dishes as well as in mustard pots. Rubber bands contain sulfur, which is why rubber leaves black stripes on the metal. The black product left after sulfur corrosion is the chemical corrosion of the silver metal, and not a stain. When the black product is removed by polishing, a thin layer of the base silver metal is actually being removed.

Some conversion products reduce the sulfide on the silver metal, leaving it a whitish color. Some preventive precautions that can help preserve silver include:

· Avoid touching polished surfaces with greases and salts, as these tarnish silver.

· Handle any silver product with care due to its soft nature. Silver can easily become dented when handled roughly.

· Avoid using the silver in environments that have sulfur products. Sulfur corrodes the surface of silver, forming black sulfide.

· Avoid storing objects made of silver in open air as they collect dust, which in turn absorbs moisture and corrodes the metal.

· Silver should be kept in a dry ventilated environment that is free from sulfurous contents.

· Avoid using harsh chemicals and abrasives, as these can damage silver or deposit a layer of another metal that may damage it.

· A coating may be applied, although it is not recommended. It is best to consult an expert when considering applying a coating to silver.


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