Metals corrode or rust. That fact is usually found out after something expensive made of metal is ruined. Preventing rust may be as simple as painting the metal surface to be protected, but not all surfaces can be painted and some that are painted still rust anyway. Rust can be considered as a slow destructive fire. Rust is oxidation where the metal reacts with oxygen creating rust. Rapid oxidation is fire.
To prevent rust is to prevent the metal surface from coming in contact with dissimilar metals and preventing bare surfaces from being exposed to oxygen. Corrosion of metals can occur when two different metal types are in contact with one another such as aluminum and copper. Rust is the formation of iron oxides as the metal is being eaten away.
Painting Metal to Prevent Rust
The most common method of preventing rust from forming on ferrous metals such as iron or steel is to paint all of the exposed surfaces. The problem is that the tiniest spot where the paint may get damaged will allow rust to form. Paint is just a barrier, and there are many types and grades of paint of which some are unsuitable for metal.
The most common cause for paint to fail to protect metal from rust is poor preparation of the surface. It is easy to grab a can of rust preventing spray paint and just spray over the dirt, rust and oily substances on the metal. The areas where the surface was dirty, had oily substances on it, or already had rust will not allow the paint to bind to the metal surface correctly.
All metal surfaces being prepped to receive a coat of paint should have old loose paint removed first. If appropriate, use sandpaper, a wire brush and a scraper to remove as much loose paint as possible. Clean the entire surface to be painted with either an appropriate solvent or with a degreasing soap and water. Make sure the surface is completely dry before continuing. There are also products that can be used to protect the surface which bind to small amounts of iron oxide converting it into a paintable surface. Otherwise, after the surface is dry, coat it with a suitable metal primer that can even include built-in rust preventatives.
After the primer is completely dry, paint the metal surface with a couple of coats of high quality metal paint. There are metal paints available that are designed to assist in the formation of rust such as the Krylon brand of paints at Krylon.com. Every little bit helps when trying to prevent rust. If spray paint is purchased in spray cans for the painting project, it is a good idea to also purchase a small container of the same color that can be brushed on as needed to fix paint nicks and scratches. Realize that paint is not permanent. Any number of factors can cause paint to lose its bond with the metal surface. It is a simple fact that is often ignored, but things do need to be repainted to protect them.
Some surfaces were never meant to be painted and need to be protected with another sort of barrier. The inside of gun barrels is one example. Gun barrels are made of steel, and the bare surface inside the barrel will quickly rust if not treated with a barrier such as oil. Tools such as some wrenches and most garden tools also have bare metal surfaces that need protection. Even stainless steel and chromed metal objects can rust.
Chemical protectants are usually reapplied after each use of the tool or surface. When a shovel is used in the garden it should be sprayed off with a garden hose until all debris is removed and then have a barrier treatment applied to prevent rust. The best rust preventative for use on garden tools is WD-40. It is a water displacement chemical made from fish and is excellent for use on tools that are often used.
Surfaces of firearms and other special tools and metal equipment need to be coated with a barrier film that is easy to apply and will not attract dust that can turn the film into a sticky gunk. Teflon based gun oils are excellent for protecting the bare surface of the inside of the barrel and other bare metal surfaces of firearms and work great on tools and other sporting equipment. A good Teflon based oil is manufactured by Remington and is known as Rem Oil.
Silicone impregnated wiping cloths are good to use to wipe down tools and firearms as well as fishing equipment and other sporting goods. A superb wiping cloth that provides an excellent barrier film to protect against rust is called the Tuf-Cloth and is available at Sentrysolutions.com.