Bluing is a process of applying a protective finish to steel to prevent rust and corrosion. It is commonly used on firearms, as well as other metal objects. The process involves creating a thin layer of magnetite (Fe3O4) on the surface of the metal. Magnetite is a black oxide of iron that is highly resistant to corrosion.
There are several different methods for bluing a gun. The most common method is hot bluing, which involves heating the metal to a high temperature and then applying a bluing solution. Other methods include cold bluing, which is done at room temperature, and rust bluing, which uses a chemical reaction to create the magnetite layer.
