Cleanliness

• One way to avoid corrosion is to keep metals dry and clean. Metal tools for instance, will rust if left damp or out in the changing temperatures from night to day. Care should be taken that metal is well oiled (which puts a layer of oil between contaminants and the metal) when appropriate, and that unnecessary exposure to the elements is avoided. However, this isn't always possible with things like pylons that hold up electric cables or with support docks kept in salt water.
  
  

Paints and Finishes

• Metals are often coated with specially formulated paints to prevent corrosion. The paints act as sealants, completely isolating the metals from any forces that might interact with them. Normal paints, while they may look like they create a complete layer between the metal and the environment, allow all sorts of contaminants. Paints that are formulated like sealants though will stop air, water and other elements from coming into contact with the metal, preventing corrosion. In other circumstances though, metals may be coated with other materials as a way to add an extra layer of protection.
  
  

Multiple Materials

• There are some materials which are not resistant to corrosion, but experience a rate of corrosion that is very slow. Metals, such as zinc, are often used as a protective coating for other metals, because zinc corrodes, but at a slow pace. This is the case when making galvanized steel. Steel is wrapped in zinc, which acts as a buffer and keeps out contaminants and protects the steel beneath. However, zinc, magnesium, cadmium and other metals which are used as preventative coatings, will eventually wear away from the metal they were protecting due to corrosion. This means that either the coating (or another piece of metal whose coating hasn't worn away) will need to be replaced if the protection is to be renewed.