Bluing is most commonly used by gun manufacturers, gunsmiths, and gun owners to improve the cosmetic appearance of and provide a measure of corrosion resistance to their firearms. It is also used by machinists, to protect and beautify tools made for their own use.
Bluing is a particular chemical treatment used to blacken objects made of iron, steel, brass and aluminium, yielding a darker surface colour that tends towards bluish black. The treatment is used to improve the appearance of the metal and guarantee non-stick properties and corrosion protection.
Bluing gun parts can preserve the appearance and performance of your gun. However, since bluing does not last forever, you will need to reblue your gun occasionally. High-quality bluing can last for decades, especially if humidity is low in your area and you keep your weapon dry and clean.
There are two reasons for using it — one is that the oxide layer that gives blued steel its beautiful color helps prevent corrosion and rusting, and the other is that it looks great. Heat-bluing is not the only way to blue steel, by the way — the oxide layer can be produced by chemical treatment as well.
Does bluing prevent rust? Cold bluing is a controlled oxidation of ferrous metals similar to rust. Whether cold or hot blued, these metals should be treated with a wax, lacquer or water displacing oil to reduce exposure to corrosion causing moisture.
Dirt and oils further the discoloration, which no amount of bleach can combat. Used for centuries, old-fashioned laundry bluing is the most effective and environmentally friendly way to whiten your whites.
All blued parts still require oiling to prevent rust. Bluing, being a chemical conversion coating, is not as robust against wear and corrosion resistance as plated coatings, and is typically no thicker than 2.5 micrometres (0.0001 inches).
By mechanically pre-cleaning the workpiece, both the natural oxide layer and other contaminants on the aluminum can be removed. The color of the bluing achieved can then vary from dark gray to black, depending on the aluminum alloy. Alternatively, aluminum bluing can also be used as a 1:1 dilution with water.
Cerakote is the global standard for firearm finishes, offering unmatched corrosion protection. It far exceeds traditional bluing in corrosion and chemical resistance, as well as durability, scratch resistance, and wear protection.
Airbrush or Spray Gun Application
DuraCoat® Clear is an extremely versatile finish. It can be applied over DuraCoat®, bluing, stainless – almost any firearm surface that needs protection can benefit from DuraCoat® Clear. When applied over bluing, DuraCoat® Clear helps prevent rusting and pitting.
As color experts would explain it, the proof can be seen in the spectrographic comparison of the two whites — the one with blue added will reflect more light, making it appear whitest. This is why homemakers looking to return their white clothes to their original sparking white color use Mrs. Stewart's Bluing.
A finishing process called “blueing” occurs when steel acquires a characteristically blue-to-black surface finish following the application of a protective coating. This process represents one subset of black oxide coatings.
Depending on the gun's age, monetary value, and sentimental value, you can either have the gun re-blued professionally or restore the bluing yourself.
Quenching is a metal heat treatment process that is done by cooling a metal for it to acquire adjusted mechanical properties. Tempering, alternatively, heats it to a high temperature before cooling it through different media, helping the product reduce internal stresses and lessen brittleness.
Annealing is a heat treatment process that changes the physical and sometimes also the chemical properties of a material to increase ductility and reduce the hardness to make it more workable. The annealing process requires the material above its recrystallization temperature for a set amount of time before cooling.
Blue steel is not as rust-resistant as stainless steel.
The complete curing process takes about 3-4 weeks to finish, so you might find yourself babysitting your gun at times during this period. If you see surface rust start to form on the barrel, apply a light coat of lubricant and wipe the barrel off.
Bluing is not permanent and rinses out over time leaving dingy or yellowed whites. A commercial bluing product allows the consumer to add the bluing back into the fabric to restore whiteness. On the same principle, bluing is sometimes used by white-haired people in a blue rinse.
But don't let that discourage you from other options. If you're looking for the best way to protect your investment, your best bets might be Cerakote, Duracoat, or bluing.
Black steel refers to steel that has not undergone a galvanisation process for corrosive protection. The steel instead undergoes a chemical process called blackening, resulting in the formation of a hardened iron oxide or magnetite surface.
Hot gun bluing is the most common bluing technique offered by most firearm manufacturers. It's a very durable finish applied on a variety of steels. The main benefit of the hot bluing method is gun protection from corrosion. This method extends the life of a gun and restores it.