Class 1A: Chemical conversion coatings are intended to provide corrosion prevention when left unpainted as well as to improve adhesion of paint finish systems on aluminum and aluminum alloys. May be used on tanks, tubing, and component structures where paint finishes are not required for the exterior surfaces but are required for the interior surfaces.

Class 3: Chemical conversion coatings are intended for use as a corrosion preventative film for electrical and electronic applications where lower resistant contacts, relative to Class 1A coatings, and anodic coatings in accordance with Mil-A-8625, are required. The primary difference between a Class 1A and a Class 3 coating is thickness.