6.1.2 Class 3. Class 3 chemical conversion coatings are intended for use as a corrosion preventive 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 (see 6.1.2.1). Coating thickness is varied by immersion time, and as a result, the same conversion material can be listed on QPL-81706 for both classes. Because class 3 coatings are thinner they are more susceptible to corrosion than class 1A coatings. If it is required to paint areas surrounding electrical contacts, class 3 coatings improve adhesion of paint systems on aluminum and aluminum alloys.