Tin can be plated wither matte or bright. Although the characteristics of each are comparable. Tin does not tarnish easily, making it a good choice as a decorative finish. Unlike most other commonly plated metals, zinc protects the substrate by sacrificing itself and thus corrodes before the base metal. For corrosion protection, chromates are applied over the zinc.
Chromates are chemical conversion coatings.
The substrate metal participates in the coating reaction and becomes a component of the coating. The collaboration has a profound effect on the properties of the coating. Among the metals commonly chromated are zinc, zinc die casting, steel, aluminum, and sometimes copper and silver. It has a slightly iridescent blue appearance.