What is the primary function of zinc chromate or wash primers?

The primary function of zinc chromate or wash primers is to inhibit corrosion. Zinc chromate is widely used in aircraft and other metal structures as a protective coating due to its exceptional ability to provide a corrosion-resistant barrier. When applied to metal surfaces, it forms a protective layer that prevents moisture and oxygen from reaching the underlying metal, which are both essential components for corrosion to occur.

Zinc chromate works by providing cathodic protection to the substrate, meaning if corrosion begins to form, the zinc will corrode preferentially instead of the substrate material. Additionally, it adheres well to metal surfaces, promoting adhesion for subsequent layers of paint or primer, which can further enhance the protective qualities of the overall finish.

While pigments might contribute to aesthetics or drying characteristics, those functions are not the primary purpose of zinc chromate or wash primers in corrosion prevention and protection. Hence, the focus is rightly placed on their role in inhibiting corrosion.