VCI is an abbreviation for Vapor Corrosion Inhibitor or Volatile Corrosion Inhibitor. (Also known as VpCIs or Vapor Phase Corrosion Inhibitors.) These corrosion inhibiting compounds are coated on paper or polyethylene bags, and have sufficient vapor pressure to release molecules into the air. Due to their polarity, the VCI molecules are attracted to the surface of metal, just like a magnet. VCI molecules move from the paper or film directly to the surface of metals. When these compounds come in contact with metal surfaces they form a very thin molecular layer.

Corrosion begins when an electrolyte (water, oxygen, humidity) is present on the surface of a metal. When this happens, electrons then flow from high-energy areas of the metal to low energy areas in a loop, through the electrolyte. The corrosion process results in the formation of oxidation on the metal surface. Green Packaging’s VCI (Volatile Corrosion Inhibitors) slow or stop this reaction by passivating the surface and inhibiting or depressing the electro-chemical mechanism that triggers oxidation, i.e. the current flow from anode to cathode.