|Tin-Zinc is one of several zinc alloy coatings that was created to replace cadmium. Tin-zinc is an engineering coating that has a dull matt gray appearance. When chromated it will have an iridescent yellow to blue green hue. The coating is not meant to be cosmetic.
Tin zinc is very good for solderability and does not form tin whiskers. The coating will be maintains its solderability even after long periods of storage.
Tin zinc is a very soft coating with excellent ductility and formability. The coating offers the greatest corrosion resistance of all zinc alloys in the presence of sulfur dioxide.
One downside to the coating besides its very non cosmetic appearance is its softness. The coating can scratch easily.
A tin-zinc deposit will have between 25-30% tin with the balance being zinc. This coating has successfully been used to replace cadmium on fasteners used on landing gear components for Airbus.