Does silver get black when it gets old and dirty? And does this affect the melt value? – John in Frenso, CA

When silver comes in contact with oxygen it oxidizes or turns black, this process is called tarnishing. No matter what form of silver your items are, sterling silver and pure silver alike tarnishes. The black/greenish substance that rubs off is called silver sulfate. Silver tarnishes not based on the type of silver, but based on the silver item’s environment. When materials like wool, rubber, fossil fuels and latex come in contact with silver it causes the item to tarnish more quickly. Also, the climate can affect this process. High humidity results in silver tarnishing faster and results in a darker and blacker form of tarnish build on the item.

As for the second part of the question, tarnish does NOT affect the melt value of items. Refiners will take silver items, not matter the condition. If you have scrap metal pieces, it could be to your benefit to not clean them. Tarnish does not just lay on the surface of silver, it is chemically bound to it. Harsh silver cleaning treatments could remove some of the silver content and affect its value.

As a warning, you should never clean silver with other metal items. A chemical reaction might occur resulting in a loss of silver off the item.

Note: If you have silver coins, you may want to be more careful in how you clean them. If you use a harsh cleaner or applicator you could destroy the original surface of the coin, significantly decreasing its numismatic value (more than its precious metal value). Consulting a coin dealer before you clean silver coins may be in your best interest.