All metals react with oxygen in the atmosphere to form an oxide film on the surface. Unfortunately, the iron oxide formed on ordinary carbon steel continues to oxidize, causing the rust to continuously expand, eventually forming holes. The carbon steel surface can be secured by electroplating with paint or oxidation-resistant metals (for example, zinc, nickel and chromium), but, as is known, this protection is only a thin film. If the protective layer is destroyed, the underlying steel begins to rust.