Rust occurs when metal is exposed to oxygen and moisture. The process that leaves behind that ugly reddish oxide on metal is called oxidation. There are several products available at hardware stores that will prevent rust from forming and protect metal items. Some products are better than others for preventing rust and depend on what you are protecting.
Pastes and Waxes
Pastes and waxes provide a moisture-resistant and oxygen-proof barrier between metal and the elements. However, one downside to pastes and waxes are that they require reapplication. Automotive Paste Wax, for example, is one product for metal machinery designed to reduce the friction between rubbing metals and provide a protective barrier.
Anti-corrosive paint works similarly to wax and paste, but it doesn't need constant reapplication. Surface cleanliness and preparation is essential to application because all moisture and rust must be removed to prevent them from getting trapped under the paint. A metal surface should be roughed up with a wire brush to ensure good adhesion. Anti-corrosive paint is widely available and also provides a barrier that will not crack or blister when applied to properly prepared metal surfaces.
Spray-on rust preventive oils and lubes are effective for small tools and small metal parts. This product can be ideal for smaller tools because it will not make a tool's grip slippery but will protect it from oxidation. Common rust preventive spray-ons are WD-40, Starrett M1, LPS-1 and LPS-3. Like rust preventive waxes and pastes, a spray-on also requires constant reapplication.
Zinc coating, also known as galvanising, is considered one of the best rust preventive methods for metal products. Zinc coating is applied through four methods: hot dipping, electroplating, spray galvanising or zinc-rich painting. Hot dipping is the most common method because it provides the thickest, most durable zinc coat for protection. Galvanising often requires professional service but will result in an extremely rustproof metal.