All metals with the exception of the precious group (gold, palladium, platinum, rhodium) are subject to tarnishing. This is typically seen as a darkening or discoloration on the deposit. The occurrence of the tarnish is exacerbated by:
- Choice of Packaging Material (sulfur bearing paper products can greatly accelerate tarnishing, especially on silver products)
To minimize tarnishing, many products receive a post plate anti-tarnish conversion coating which will effectively seal off the plated surface from the precursors of oxidation. Typical of these coatings are chromates, triazoles, clear powder coatings and lacquers. Mechanical barriers are also used to minimize exposure to oxygen and moisture. Typical of these are desiccants and various types of protective wraps.
Advanced Plating Technologies can provide many options to minimize the tarnishing of a plated deposit including nitrogen bagging. In nitrogen bagging the oxygen that is responsible for forming metal oxides is removed by filling the bag with pure nitrogen. APT will guarantee protection from tarnish for your product for up to one year if nitrogen bagging is specified.