Chemical Film/Conversion
Chemical conversion coatings are used as a corrosion preventive film for metal that is left unpainted, improves electrical conductivity, and can improve the adhesion of paint finishes to aluminum and aluminum alloys. This coating is fragile, so often Anodization is preferred for high use areas. Chemical film is also known as chromate, iridite, alodine, and aluminum passivation, and does not add thickness.
Military Specifications: MIL-DTL-5541F
Type I, Class 1a: Gold
Gold gives superior corrosion resistance than clear or light gold.
Type II, Class: Clear
ROHS Compliant
Type I, Class 3: Light Gold
Light Gold provides lower electrical resistance than Gold