Corrosion is a numismatist’s worst nightmare. Even if your collection is well cared for and carefully stored, external influences can still damage the material of your valuable coins. This is because the air contains several substances which react with metals, leading to corrosion. Nitrous gases are one example, in addition to ozone and other corrosive gases, such as hydrogen sulphides, ammonia, carbonyl sulphide and chlorine compounds. Problems with traditional methods of protecting coins There are currently different ways for collectors to protect their coins: With regard to regular cleaning, it is important to consider that all contact with the precious surface of the coin will wear it. So, less is more. This is also true for sealing coins with varnish, wax or oil. The inestimable risks involved in these processes mean they do more harm than good. The tried-and-tested coin capsule protects from mechanical damage and the acids found on human skin, but it cannot offer permanent protection from corrosive gases.