My friend Dan asked me why her Pandora Charms are turning black. And I told her that Pandora Charms are made by sterling silver. The reason is the silver turn to black.
An important factor is a strong affinity between silver and sulfur. Scientists have determined that silver can easily form a very difficult silver salt (Ag2S) when it encounters hydrogen sulfide gas or sulfur ions in the air. The main component of the mine), this chemical change can occur in a very small amount of silver. As long as silver encounters several trillion to several tens of trillions of hydrogen sulfide or sulfur ions in the air, the following chemistry occurs. reaction:
4Ag+2H2S+O2=2Ag2S (black product)+2H2O
As a result of the reaction, silver sulfide is produced on the surface of the silver. Since the silver sulfide is greyish black, as the reaction progresses, the silver sulfide increases and the color of the silver surface gradually changes from white to yellow to grey and finally becomes black.
Pandora sterling silver charm is easy to oxidize, oxidizes yellow with sulfur, and turns black.
In general, human skin secretions have a protective effect on silver ornaments. Most of them are worn brighter and brighter. Only a few people, because of personal physique, wear more and more black, but not necessarily bad health. When silver hits sulfur, it turns black. This can be proved by wiping the silver product with boiled egg yolk containing more sulfur. Some people have more sulfur in their sweat, and Pandora silver charm is easy to turn black. This kind of constitution is not suitable for wearing Pandora silver charms. Blackened Pandora silver charms can be applied to the cloth with toothpaste to erase.