Blueing is a thin protective layer of black iron oxide (Fe3OR4) that is intended to provide nominal rust protection to the metal of the weapon. However, over time this layer wears out and you need to renew it to restore the appearance of the weapon. Depending on the age of the weapon, its monetary and sentimental value, you can have it professionally repaved or restore the blueing yourself.
Part 1 of 4: Decide How to Restore Blueing
Step 1. Take into account how much the previous bluing has worn away
If most of the original bluing still remains, you can probably touch up the bluing yourself with a cold bluing kit. If most of it has worn off, consider removing the rest of the old bluing and hot bluing the gun metal.
Step 2. Take into account the age of the weapon
Antique weapons from the 19th century were browned with the oxidation or vapor phase browning process. Currently, these processes are not used commercially due to the amount of time they take. There are products available on the market that will allow you to do the oxidation bluing process yourself or you can find someone to do it for you.
Old guns that have silver solders cannot be hot browned because the caustic salts used in this process will corrode them. Double-barreled shotguns typically used this kind of welding to keep the barrels properly aligned
Step 3. Consider the value of the weapon
The cost of hot bluing is significantly higher than cold bluing, so you should compare the cost of the resurfacing process you plan to use with what you spent to buy the gun in the first place and its resale value, if you were to. sell it.
You should also take into account the intrinsic value of the weapon, or what it means to you, as well as the current monetary value. If the gun is a family heirloom, you may consider spending more money to reshape it, even if the dollar value equals the cost of buying a gun at the sporting goods store
Step 4. Take into account the potential cost of the bluing process
In addition to the monetary and intrinsic value of the gun that needs to be resurfaced, you should also take into account the cost of the blueing process you plan to use.
- Cold bluing, which is described in the second section of this article, is the simplest and therefore the cheapest process, but it is also the least durable. If you plan on using your weapon a lot after cold stripping, expect this bluing to wear out pretty quickly.
- Hot bluing, which is described in the third section of this article, is more durable than cold bluing and can last longer than oxidation or vapor bluing, but requires more work and more equipment to do so. If you feel the gun deserves to be hot-blued, but you find the work involved too overwhelming to do it yourself, you'd better pay to have it done.
- Oxidative bluing, which is described in the fourth section of this article, requires slightly fewer materials than hot bluing, but more than cold bluing. Plus, it's the most time-consuming bluing process because you have to let the gun metal rest for a while to achieve the level of coloration you want. Here, too, it's best to pay someone to rust strut your gun if you find the process too overwhelming to do it yourself.
Part 2 of 4: Cold browning
Step 1. Remove the old bluing, if desired
If the original bluing is badly worn, it may be best to remove it completely before resurfacing the gun. To do this you can use one of the following chemicals:
- A phosphoric acid based automotive deoxidizer, such as Naval Jelly.
- White vinegar that contains acetic acid.
Step 2. Polish the metal of the weapon
By polishing you remove surface rust and any scratches or marks that the weapon may have suffered over the years. For this purpose you can use either a # 000 steel wool or a 600 to 1200 grit sandpaper.
Step 3. Clean the metal from the gun
How you clean the metal will depend on whether you want to bluff the entire weapon or touch up the bluing you already have.
- If you plan to blacken the entire weapon, soak the metal in a cleaning solution. Cleaning solutions you can use for this include sodium tripolyphosphate (a commercial detergent), denatured alcohol, or naphtha (if you choose to use naphtha, then you should wash the gun with a dish soap and then rinse it with hot water).
- If you plan to submerge the gun parts to clean them, use a wire basket to position the small parts and run a thin wire through the barrel to lower it into the cleaning solution and then raise it again.
- If you only plan to touch up the bluing you already have, apply a cleaning oil to the places where you want to remove the old bluing and then apply acetone with cotton balls to remove the cleaning oil (Ballistol is the trade name for a cleaning oil of this type, which is a mixture of mineral and vegetable oil, alcohol, benzyl acetate and alkaline salts). As you clean the old bluing, you may find scratches that will need to be sanded or polished.
Step 4. Slightly heat the metal
Although this process is called cold bluing, slightly heating the gun metal before bluing can help it absorb the bluing better and give it a better finish. To heat the metal, you can leave it in the sun for several hours, use a flamethrower or a tumble dryer, or put it in a regular oven at the lowest temperature.
Step 5. Apply the bluing solution
Slowly apply the solution to the area to be bluffed with a clean applicator as evenly as possible. Apply the solution in a single pass to cover small areas or in sections no more than 5 to 7.5 cm (2 to 3 inches) when covering large areas, then smooth it out with steel wool. This will prevent the bluing from getting stained.
- It is recommended to use old pure cotton T-shirts or new brushes to apply bluing in larger areas. For smaller areas, use a cotton ball, cotton swab, or flat toothpick that is no larger than the area you will be covering.
- You can wet small parts, such as screws or hard-to-cover areas, with the blueing solution. If you don't have enough bluing solution to wet a recessed area, put it in a clean spray bottle and spray it freely onto a glass (pyrex) container or plastic tray. After the area is completely covered, you can pour the leftover solution back into the jar and reuse it.
Step 6. Apply the solution several times until you get the level of bluing you want
Apply each coat with a new applicator and use a new piece of steel wool to buff each new coat.
- The more layers you apply, the darker the bluing will be. However, each new layer is less effective than the previous one. In most cases, seven coats are sufficient to achieve the blue-black finish.
- If there are spots that don't darken, start the process again. Sand the stains with 320 to 400 grit sandpaper before applying the solution again, trying to sand only the stains that do not want to come out.
Step 7. Coat the finish with gun oil once you have the bluing level you want
Apply a coat of gun oil every few hours (a few hours) and use a cotton ball to remove the old coat before applying the new one (you are basically cleaning the bluing solution with the gun oil instead of water).
Do not use cleaning oil for this process because it will remove the bluing you worked so hard to achieve
Part 3 of 4: Hot browning
Step 1. Polish the parts of the weapon that you will blue
You can also use # 000 steel wool or 600 to 1200 grit sandpaper to polish the metal.
Step 2. Prepare parts for dipping in cleaning and blueing solutions
Although your cleaning solution may not need it, the chemicals used in the hot bluing process are typically sodium hydroxide and potassium nitrate and are highly caustic. It will be easier for you to submerge the barrel if you put a soft wire through it, and it will be easier to submerge the small parts if you put them in a wire basket.
Assemble the parts now, before the cleaning step, to make it easier for you to transfer them from the cleaning tank to the bluing tank, and the basket and support wire will also be cleaned to prevent any of them from contaminating the gun parts in the bluing tank
Step 3. Soak the gun parts in a bath with the cleaning solution
Soak the parts in the bath for 10-15 minutes and scrub them while they are there to remove any oil, dirt, or grease that could get in the way of the bluing process. You can use the following chemical cleaners, as long as you read and follow the instructions for their use, handling and disposal.
Step 4. Rinse the cleaning solution with cold water
This process will not take you more than 2 or 3 minutes.
If you used dish soap to remove the cleaning chemical, you may need to use hot water to rinse it off
Step 5. Dip the gun parts in the bluing solution
The hot bluing solution is known as "traditional caustic black" and should be heated to a temperature between 135 and 155 degrees Celsius (275 and 311 ° F).
- Before heating the bluing solution, mix it thoroughly to remove any lumps of bluing salt that may form on the surface or bottom of the tank where the solution is.
- When dipping the barrel of the gun into the bluing solution, do so at an angle to allow any air bubbles that form to escape. Make sure to submerge the barrel completely.
- Rotate the metal basket containing the smaller parts of the weapon throughout the solution to ensure that the parts are completely coated with the blueing solution.
- Leave the pieces in the bluing solution for 15 to 30 minutes. When you see that the metal has reached the desired shade of bluing, remove them from the solution.
- If the weapon has stainless steel parts, they must be immersed in a different chemical solution that is made from a mixture of nitrates and chromates. Heat it to a temperature similar to the hydroxide and nitrate mixture.
Step 6. Rinse the bluing solution in cold water
Swirl the pieces in the cold water to help clean the bluing salts.
Step 7. Dip the weapon parts in boiling water
This will evaporate any remaining residue from the bluing solution. Simple pieces should be soaked for 5-10 minutes, while complex or decorated pieces may take up to 30 minutes.
If your weapon has welded parts, you can apply a chemical to them that will stain the welds to match the rest of the metal. To do this, use a cotton swab
Step 8. Immerse the treated parts in an oil bath to displace the water
This will protect the finish from rust, sweat, and body oil. Leave the pieces in the oil bath for 45 to 60 minutes, until they have cooled down.
Part 4 of 4: oxidation browning
Step 1. Polish the parts to be blued
Again, steel wool or 600 to 1200 grit sandpaper will work to remove any rust, marks, or scratches from the metal weapon.
Step 2. Chemically clean any remaining dirt, oil or grease
You can use any of the chemicals described in the cleaning step for cold bluing, unless the manufacturer of the oxidation bluing solution you use gives other directions. Rinse off the cleaning solution after using it.
Step 3. Coat the metal parts of the weapon with the oxidation bluing solution
This solution is normally a mixture of hydrochloric and nitric acid and it stimulates oxidation in the metal, but it does so evenly.
- Instead of coating the parts with the acid solution, you can place an open container of the acid solution along with the weapon parts in a hood and seal it for a period of 12 hours. The acid evaporates from the container and condenses around the metal of the weapon. This method is called vapor phase blueing.
- Another way is to coat the metal parts of the weapon with the oxidation bluing solution and then place them in a fume hood (or a wet hood, in this case) also for 12 hours. Often times, a first coat is applied as a base before coating the pieces a second time and then placed in the wet hood.
Step 4. Submerge the metal parts of the weapon in boiling distilled water
This will stop the oxidation process by removing the acidic solution.
Step 5. Scrub the rust from the red oxide that forms and leaves the black oxide finish underneath
Surface rust is removed as usual with a brush or carding disc that has very soft and fine wire bristles.
Step 6. Repeat the acid treatment, return to a boil and scrub until you have achieved the desired level of bluing
In some cases, the metal may develop the deepest color possible, making further blueing treatments counterproductive.
Step 7. Coat the gun parts with oil
The oil inhibits rust formation and protects the metal finish from dirt, sweat, body oil, and wear. Once you've applied the oil, let the pieces sit overnight before assembling the weapon.
- Before using any of the blueing processes described above, make sure the firearm is not loaded! Also remove the grip or magazine from the weapon.
- Work in an area with good ventilation for all blueing processes. The caustic salts used for hot bluing are particularly harmful.
- Do not attempt the hot bluing process on aluminum. This would create a violent reaction with the caustic salt bath that could cause severe chemical burns.