Constructing your own humidity cabinet to blue metal is a first step in learning to apply a decorative and preservative finish to steel parts.

By Leo Radovich

There are a variety of processes, collectively known as “bluing”, which are used to achieve a blue or black finish on gun steel. Bluing is actually a type of controlled oxidation, a form of rust, that yields some protection to the metal. A common process requires the immersion of gun parts in a hot caustic bath, followed by rinsing and oiling after the desired color and intensity are achieved. This process is relatively quick and can be automated, which is why most large-scale manufacturers use it.