Iron can be prevented from rusting by covering the surface with paint, oil or grease or by using a process called electroplating to apply a thin layer of non-reactive metal, such as copper, nickel or chromium. This is known as barrier protection and helps to prevent rusting by stopping oxygen and moisture from having contact with the surface of the iron.
Rusting is the more common name for oxidation, which causes the iron molecules to lose electrons and weaken the structure of the metal. Rust itself is permeable to air and moisture, so once a first layer of rust has formed, the process continues until prevented or all the iron has been converted to iron oxide (rust).
Another means of protecting iron from rust, called sacrificial protection, involves using a process called galvanization to apply a thin layer of a more reactive metal to the surface of the iron. This protects the iron from oxidation as the more reactive metal, which is commonly zinc or magnesium, is oxidized more readily than iron. These metals can also be dissolved in paints and then used to coat the surface more effectively. Alkaline chromate and alkaline phosphate are also used as anti-rust treatments. These strongly alkaline solutions form a thin film of insoluble iron phosphate on the surface of the object treated.