Anodizing, Bluing, Parkerizing, Nickel Plating, Cerakoting… choosing a coating for your firearm or simply determining which coatings are on the firearms you already own can be a daunting task. It is also near impossible to select a “best coating” as that choice is heavily determined by how the firearm is used and maintained.
Coatings can be broken down into two main types, those that oxidize or otherwise change the chemical makeup of the existing metal’s surface, and additive coatings like paint that are applied over the existing metal and add an additional layer of thickness to the firearm’s surface.
Unlike paint or plating, anodizing is not a coating that is applied over the existing metal but is an electrochemical process that converts the surface of the metal itself. Anodizing can only be done to non-ferrous metals such as Aluminum and Titanium.
Anodizing is done by passing an electric current through an electrolyte bath containing the aluminum piece. An electrolyte bath is an electrically conductive solution full of readily-available positive and negative oxygen ions. These oxygen ions are released from the electrolyte solution to combine with the aluminum atoms creating an anodic oxide structure at the surface of the aluminum piece being anodized. Anodizing slightly increases the dimensions of the piece by increasing the thickness of the oxidative layer. Since the anodizing actually becomes part of the underlying aluminum substrate, it can not peel or chip off like paint. The anodizing process also creates a uniform and porous finish that allows for additional coatings and better holds lubricants
Type III Anodizing of aluminum is the current Mil-spec and creates one of the hardest finishes available.
One relatively unknown benefit of anodizing is that it is somewhat environmentally friendly, producing very few harmful byproducts.
Cerakote is a ceramic-based gun finish that gives the firearm a very hard and durable finish and is extremely heat resistant. Cerakote can be applied to a variety of surfaces and is available in many colors and patterns. It is one of the most durable and low-maintenance firearm finishes available. Since Cerakote is a coating that adds a layer of thickness (typically .0015 to .002 thickness), it should only be used on firearm exteriors where this thickness can be tolerated.
A black nitride finish is created when an additional step called postoxidation is added to the ferritic nitrocarburizing process. Postoxidation creates a layer of black oxide that greatly increases the corrosion resistance of the treated substrate while leaving an aesthetically attractive black color. The ferritic nitrocarburizing process diffuses nitrogen and carbon into the surface of ferrous metals creating a two-part surface (an outer iron nitride layer and an inner nitrogen diffusion layer). Nitrogen and carbon (hence the name) are absorbed into the surface of the metal creating reproducible and uniform layers with a predetermined thickness across all areas of the metal.
DLC (Diamond Like Coating)
DLC is a carbon layer that is about as hard as diamond and is suitable for heavily used guns. It is a physical vapor deposition (PVD) process resulting in an extremely thin coating thickness (less than .005″) that can be applied to carbon steel, stainless steel and aluminums. It is a dark charcoal color when but appears black when oiled. A unique attribute of this coating is that it reflects the gun part’s surface before the process (matte surfaces appear matte again, mirror polished surfaces keep their mirror surface) after the coating process.
Bluing (Black Oxide)
One of the cheapest and longest-used coatings is bluing. Many of us will be familiar with the combination of a blued barrel with the walnut stock of a cherished hunting rifle. Used on ferrous metals, blueing is used both to protect the underlying metal from corrosion and to reduce glare. The bluing process is an electrochemical process that converts the surface iron in the steel to black oxide. The black oxide finishing process is an electrochemical reaction that oxidizes the metal’s surface transforming the surface iron to magnetite therefore not changing the physical dimensions of the piece. When combined with a frequent, light coating of oil, bluing makes for a reliable, cost-effective, and timeless coating for your firearm.
Many of us are familiar with Parkerized firearms as this is both the standard coating used by the military as well as the finishing process used to protect Glock pistol slides. Parkerizing (named after the Parker Rust-Proof Phosphating Company) can only be used on ferrous metals such as steel and alloy steel and creates a surface coating that improves wear resistance and increased protection from corrosion. Phosphating is a process in which the piece is immersed in phosphoric acid solution creating a protective iron-phosphate layer and a dark grey matte finish. Like bluing, it does require frequent oiling to prevent corrosion.
We are currently exploring several of the coating options discussed above and will update this article and our social media with photos of examples as we complete projects.