Gun Bluing 101-How to Blue a Gun

This article is part ofCRATEX Gunsmithing Tools Series. For the full article click here

If you’re in a gun, you might have heard the term gun bluing kit before.
Various forms of bluing have been used by forged wonders and pistol friends for centuries to protect guns from wear and damage, but you might still askwhich pistol is bluing.

Bluing or black-oxide is a process of treating steel to create a thin protective cover around it. It works, by turning rust, into black iron oxide.
The blue-black image of black iron oxide gives the name of this process. It can be carried out on pistol barrels and other firearms components.
There are various methods to blue weft threads, such ashot bluing, cold bluing, rust bluing, niter-bluing, charcoal-bluing and heat-luing.

The pistol refinement is one of the most pleasing phases of forging work.
Few gunsmithing operations are as rewarding as a rusted and badly abused weapon that has been turned into a beautiful, artful, bluish, bluish-black finished arm. It turns a worn-out weapon into one that looks completely new.

Before, the arrival of the modern solutions for the bluish rifles, which was a weapon, the unique, blue-black look was a long process that requires many hours of intense, hands-on work.

Hot Bluing

Hot Gun Bluing is the most common bluing technique offered by most manufacturers of firearms. It is a very durable surface that is applied on a variety of steels. The main advantage of the hot bluing process is the cannon protection against corrosion. This method extends the life of a pistol and restores it .

Follow the next 6 steps to get a hot gunmetal blue process like real gunsmith..

Step 1 Explode and Polishing

Use steel wool to remove any scars, loose rust, or pitting from the Armmetall. Take the gun all the way. Anything you don’t separate will melt salt in it, and it can be significantly more challenging to disassemble afterbluing steel. You must also remove all feathers that you do not want blue. Swab the parts, they don’t have to be flawless, but get the big stuff out.

The appropriate chemicals for the bluing process are caustic chemicals. Always wear rubber gloves while you work with these chemicals.

Step 2 Soaking and Rinse

Parts should be dipped into the bath for 15 minutes and scrubbed while they are dipped in to remove dirt, oil or fat that could be obtained by the bluing process. You can use any chemical cleanser such as sodium triphosphate, naphtha, denatured alcohol and acetone. Rinse the cleaning solution in a few minutes.

Step 3 plunge the Gun parts into the bluing solution

The bluing solution used in hot bluing is a caustic salt mixture of potassium nitrate and sodium hydroxide, which is recognized as a “traditional caustic black”. The caustic salt mixture must be heated in a metal basket to a temperature of 275 to 310 degrees F, with the composition of the traditional caustic black having to be used.

Leave the pistol in the bluing solution of 15 to 30 minutes to stay.
Check whether the metal has reached the desired hue of the bluing, and remove it from the solution at this time.

Step 4 Kaltwasser flushing

Turn the parts through the cold water to wash off the bluing salts. Let the air dry for 3 minutes.

Step 5 Boiling

Rinse after the cold water, put the gun in boiling water. It will cook all the remaining bluing leftovers. Simple parts have to be soaked for 15 to 20 minutes, while complex or decorated parts should be soaked for about 45 minutes.

Step 6 End Process

Soak the treated rifle parts in a bath. It protects the finish from sweat, body oil and, of course, rust. Leave the parts in the oil bath for an hour until they are cooled down, and you have successfully finished the gun bluing task.

Cold Bluing

Cold Bluing is a process in which no heat is needed. Cold bluing is not particularly resistant to wood wear, it also does not offer a high level of rust protection. As a rule, there is a sufficient cosmetic retouching of the equipment of a pistol when applied and additionally oiled on a regular basis. However, rust bluing of small areas is often “better hitting the bluing target” than any other cold bluing process. Read the following steps and learnhow to cold a pistol with cold blue.

Step 1 Cleaning and Polishing

Polish the metal with the sandpaper, like you do with one of the other bluing processes, but how you want to clean the arm depends on whether you’re blue or touch existing bluing.

Step 2 Using the Bluing Solution

Carefully distribute the solution on the part to be bleed as evenly as possible, and use a clean applicator. Use the solution in a single pass to cover small areas, or in parts that are not larger than 4 to 5 inches if they cover large areas, and then smooth it with sandpaper. It will prevent the bluing from “chaotic”.

Repeat the application of the solution several times until you have received the desired bluing result.

Step 3 Fine adjustment

“Spice up” the finish with pistol oil as soon as you reach the desired bluing level.
Spread a layer of pistol oil a few more time, applying a cotton wool ball to remove the previous layer from the spread of a new layer.

The cleaning oil is not used at this stage, as it is the bluing.

Rust Bluing

Rust bluing is a great blue-black finish that was used by firearms companies before 1940 when the hot bluing was invented. Hot-bluing isn’t much better, but it’s much less labor-intensive.

Rust bluing is nowadays very popular for custom hobbyists and blacksmiths due to the quality and durability of the surface, which can be achieved without too much equipment. Rust bluing is a process to make rust out of steel in a controlled environment.

Niter Bluing

The Niter Bluing is also known as a fire-bluing process that creates vivid colors, but they are not always durable. It works best on pins and screws, because they are connected with wear and movement. Niter bluing can create any shading between straw and dark blue.

In the process, the gun is soaked into a hot liquid potassium nitrate, which produces a uniformly dyed finish. Like all other bluing methods, the most important step is the metal preparation.

The metal surfaces are ground with a block in order to remove all imperfections and then to polish to a mirror just before the bluing process, thereby avoiding oxidation of the steel. Even though the blues make a shiny finish, it’s not as hard-wearing as hot bluing, as it creates a patina color with wear.

Charcoal Bluing

It is one of the traditional bluing methods used on many fine firearms. The process involves packing the steel in charcoal and the “baking” at approx. 800for a few hours.

This process will be created by SW sometime after WWI. Smith Wesson hired the American Gas Furnace Company to develop abluing oil, which contained special rolling oil. The cannons were placed in a rotating drum loaded with wheat oil and charcoal, and the drums were heated in the oven, while the oil-coal mix turned around the parts inside the drum.

“Catch” the right texture and the shadow of the original charcoal-bluing surface is mostly dependent on the underlying metal polish. The end result is a shiny blue-black finish, which is very durable. A charcoal-blued high-gloss part will produce a mirror-like surface, which is in no case a second.


The bluing process is often accelerated and intensifies with the heat medium. All items become more elastic and smooth when they are heated.

The heat-or flame-blood-method is practically the heat treatment, which gives the temperature-based colour, and the ingredients present during the heating. By heating up pistol parts, you can reach colors from straw to black and deep blue. If you “remove the heat from the gun parts at the right time,” you can get a discreet blue color, just like the Niter Bluing.

How can you make a Gun blue again?

In the next 5 steps you will find out how to make a pistol new blue.

Step 1 Polishing

Use steel wool to remove any pitting, loose rust or scars from the gun.

Step 2 Cleaning

Clean any oil, grease or dirt that remains chemically. They can use sodium, naphtha, triphosphate, denatured alcohol and acetone. Then rinse the cleaning solution.

Step 3 Coating

Transfer the pistol with a mixture of nitric acid and hydrochloric acid into the metal container. The acid solution forces the metal to rust, but to act so evenly.

Step 4 Boiling

Soak the pistol in boiling water. It stops the rusting by removing the acid solution.

Step 5 Scrubbing

Scrubbing off the red oxidrust that has formed, so that the black oxide is below it. Remove the rusted section with a ball of steel wool.

The acid process, the boil and the scrub again, until you have the desired number of bluing.

Step 6 Apply Oil

Apply the oil to rifle pistol parts. The oil prevents the formation of rust and protects the metal finish from sweat, body oil, wear and dirt. As soon as you spread the oil, leave the parts to stand overnight before mounting.

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