Steel components are coated with cadmium to prevent corrosion. Metal is broken down and converted into compounds like oxides, hydroxides, or sulfates by the natural chemical or electrochemical process of corrosion.

Cadmium plating in aviation guarantees material compatibility and acts as a protective barrier when steel components come into touch with other metals. Degradation of the plating manifests as surface mottling that is white, brown, or black.

Cadmium deterioration is most frequently seen inside airplane fuel tanks, where exposure to chemicals and the environment speeds up the coating’s disintegration.