Burnishing is an iron oxide coating (Fe3OR4) whose function is to protect the metal of a weapon from rust. Over time, however, this protection can go away and it is therefore necessary to renew it to give the weapon its original appearance. Depending on the age of the gun, its economic value and sentimental value, you can have the bluing renewed by a professional or try to do it yourself.
Steps
Method 1 of 4: Decide how to Renew the Burnishing
Step 1. Check how much of the old bluing is gone
If most of the original coating is still intact, you may want to touch it up yourself with a cold bluing kit. If, on the other hand, a large part of the coating has worn out, you can consider removing the rest and proceeding with a hot bluing.
Step 2. Consider the age of the weapon
Ancient weapons, also built in the nineteenth century, underwent a mixed burnishing process: both rust burnishing and evaporation. These procedures are no longer carried out as they are now obsolete. There are products on the market that allow you to do a rust bluing yourself, or you can find someone to do it for you.
Ancient weapons, which feature silver or brass welds, cannot be hot burnished, because the caustic salts used in the process would consume the silver. Double-barreled shotguns usually used this type of welding or brass plating to keep the two barrels well aligned
Step 3. Consider the value of the weapon
Hot bluing costs a lot more than cold bluing, so you have to consider the cost of renewing the bluing compared to how much you would spend to repurchase the gun and how much you would earn by reselling it.
You should also consider the intrinsic value of the weapon, its significance to you, as well as its current monetary value. If the weapon is part of the family heirlooms, you can think about spending more on bluing, even if its monetary value is the same as a weapon bought in a sports armory
Step 4. Consider the potential cost of the bluing process
In addition to the monetary and intrinsic value of the gun to be burnished, also take into account the costs of the burnishing process you want to carry out.
- Cold bluing, described in the second part of this guide, is the simplest of the procedures, and therefore the cheapest, but it is also the one that lasts the least. If you plan to use the gun a lot after bluing, expect fast wear of the cold bluing.
- Hot bluing, described in the third part of this guide, is more durable than cold bluing and also than rust bluing, but it requires more effort and more equipment. If you think the gun deserves a hot bluing, but feel that doing the job alone is too daunting, you can consider having someone else do it.
- The rust bluing, described in the fourth part of the guide, is somewhat less aggressive on the materials than the hot process, but more aggressive than the cold one. It is also the most time-consuming process, as you have to let the gun stand for a while for it to acquire the color you want. Again, you can consider hiring someone if you think the process is too difficult for you.
Method 2 of 4: Cold Burnishing
Step 1. Remove the old bluing if you prefer
Depending on how worn the bluing is, you may want to remove it entirely before applying the new one. You can use one of the following chemicals to do this:
- A phosphoric acid based automotive rust remover such as Naval Jelly.
- White vinegar, which contains acetic acid.
Step 2. Polish the metal of the weapon
Polishing removes rust from the surface and any scratches or roughness that the weapon has suffered over the years. You can use steel wool 000 or fine sandpaper, with a grain size of 600 to 1200, for this process.
Step 3. Clean the metal of the weapon
The cleaning method you choose depends on whether you decide to brown the entire gun or touch up the existing bluing.
- If you decide to brown the entire weapon, you can soak the metal in a cleaning solution. Suitable cleaning solutions for this purpose include sodium triphosphate (a commercially available cleaner), denatured alcohol, or naphtha (if you choose to use naphtha, wash your firearm with a mild dish detergent, then rinse it with warm water).
- If you decide to soak parts of the gun to clean them, you can use a basket to hold the small parts and thread a thin cord through the barrel to lower it into the cleaning solution and rinse it again.
- If you plan to touch up only the existing bluing, you can apply a cleansing oil to the areas where you want to remove the old bluing, then apply acetone to cotton balls to remove the cleansing oil (one of these oils, a mixture of oils). minerals and vegetables, benzyl acetate and alkaline salts, can be found commercially under the name of Ballistol). As you clean the old bluing you may find marks that require grinding or polishing.
Step 4. Gently heat the metal
Although the process is cold bluing, gently heating the metal before applying the bluing can help it absorb it better to create a better finish. Heat the metal by leaving it in the sun for a few hours, with a heat gun, a hair dryer or in a traditional oven at the lowest temperature.
Step 5. Apply the bluing solution
Slowly apply the solution to the area to be browned as evenly as possible, using a clean applicator. Apply the solution in a single pass to cover small areas, or in sections no larger than 5-7cm when covering large areas, then smooth with steel wool. This way you can prevent blotchiness from appearing on the bluing.
- To apply the bluing to large areas, old cotton T-shirts or new toothbrushes are recommended. For smaller areas, use a cotton ball, swab, or flat toothpick no larger than the area to be covered.
- You can wet small parts such as screws or hard-to-cover areas directly in the bluing solution. If you don't have enough solution to wet hard-to-reach areas, put the liquid in a spray bottle and spray it liberally on the metal with a glass bowl or plastic tray underneath. Once the part is completely covered, you can pour the fallen solution into the basin or tray back into the bottle so you can use it again.
Step 6. Apply the solution several times until you get the desired level of bluing
Apply each layer with a fresh applicator and use fresh steel wool to smooth each layer.
- The more layers you apply, the darker the bluing will be; however, each new layer will be progressively less effective than the previous one. Seven layers can be enough, in many cases, to reach a final level between black and blue.
- If there are areas that do not blacken, wipe with 320-400 grit sandpaper before reapplying the solution. Try not to sand over hard areas.
Step 7. Finish finishing with gun oil once you have achieved the desired level of bluing
Apply layers of oil every few hours, using a swab to remove the previous layer before applying the new one (essentially, you need to wash the new bluing with oil instead of water).
Do not use the cleaning oil for this process, as it will remove the bluing you have been working on for so long
Method 3 of 4: Hot Burnishing
Step 1. Polish the parts of the gun to be browned
Again, you can use 000 steel wool and 600-1200 grit sandpaper to polish the metal.
Step 2. Prepare the parts to be immersed in the washing and bluing solutions
If the cleaning solution does not require it, the chemicals used in the actual burnishing process, usually potassium nitrate and sodium hydroxide, are highly caustic. It will be easier for you to submerge the gun barrel if you tuck a thin cable inside, or submerge the smaller parts if you store them in a basket.
Preparing the parts before cleaning will make it easier for you to transfer them from the cleaning tank to the burnishing tank and will also clean the support basket to prevent it from contaminating the firearm during burnishing
Step 3. Immerse the gun parts in a bath of cleaning solution
Parts should be immersed in the bath for 10-15 minutes and scrubbed while inside to remove any oil, dirt or grease that can end up in the bluing process. You can use some of the chemical cleaners mentioned earlier in the cold process cleaning, as long as you follow all the directions for use, handling and disposal of the product.
Step 4. After bathing in the cleaning solution, rinse in cold water
The rinsing should not last more than 2 or 3 minutes.
If you've used dish detergent to remove chemicals, you can also use warm water to rinse
Step 5. Immerse the gun parts in the bluing solution
The classic hot bluing solution, the "traditional caustic black", must be heated to a temperature ranging from 135 to 155 degrees centigrade.
- Before heating the bluing solution, mix it thoroughly to break up any lumps of salt that may form on the surface or bottom of the tank containing the solution.
- When you immerse the gun barrels in the solution, do so at an angle that allows any air bubbles that may form to escape. Make sure you immerse the barrel completely.
- Shake the basket containing the smaller gun parts vigorously around the solution to make sure the parts are fully coated with the bluing solution.
- Leave the gun parts in the bluing solution for 15-30 minutes. Check to see if the metal has reached the right intensity of bluing and at that point remove it from the solution.
- If your firearm has stainless steel parts, they need to be immersed in a different chemical solution, a mixture of nitrates and chromates. It will be heated to the same temperature as the nitrate hydroxide mixture.
Step 6. Rinse, after the bluing solution, in cold water
Swirl the parts in the cold water to make the salts wash away.
Step 7. Immerse the parts of the weapon in boiling water
In this way any residue of the bluing will be evaporated by boiling. The simple parts must remain in water for 5-10 minutes, the complex ones or the ornamental parts must remain immersed for up to 30 minutes.
If your weapon has welded parts, you can apply chemicals to the parts that color the welds to match the color of the metal. Use a cotton swab for this process
Step 8. Soak the treated parts in a water repellent oil bath
This will protect the finish from rust, sweat and body oils. Leave the parts in an oil bath for 45-60 minutes, until they have cooled.
Method 4 of 4: Rust Bluing
Step 1. Polish the parts that have been burnished
Again, steel wool or 600-1200 sandpaper will remove any residue of rust, scratches or roughness from the metal of the gun.
Step 2. Wash away any dirt, oil or grease that remains after the chemical process
You can use the cleaners listed in the cold bluing process if the manufacturer of the rust bluing solution does not recommend otherwise. After using the cleaning solution, rinse it off.
Step 3. Cover the metal parts of the gun with the Rust Burnishing Solution
The solution is usually a mixture of nitric and hydrochloric acid. The solution actually causes the metal to rust, but evenly.
- Instead of covering the parts with an acid solution, you can put an open container of acid solution with the weapon parts in a cabinet and seal it for 12 hours. The acids will evaporate from the container or condense around the metal of the weapon. This method is called “evaporative bluing”.
- Another variation is to cover the metal parts of the weapon with the rust bluing solution and then store it in an evaporation cabinet (in this case, a damp cabinet), again for 12 hours. Often, a first layer is applied as an imprint before covering the parts a second time and placing them in the cabinet.
Step 4. Immerse the metal parts in boiling distilled water
This will stop the rust from forming by removing the acid solution.
Step 5. Scrub away the red oxide from the rust that has formed, leaving the black oxide finish underneath
The rusty surface is normally removed with a carding brush or wheel, which have the characteristic soft and fine bristles.
Step 6. Repeat the acid treatment, boiling and scrubbing until you have reached the desired level of browning
In some cases, the metal can develop a darker pigment, making further bluing counterproductive.
Step 7. Cover the gun parts with oil
The oil inhibits the formation of rust and protects metal finishes from dirt, sweat, body oil, wear. Once the oil is applied, leave the parts overnight before assembling them.
Warnings
- Before carrying out any of the burnishing procedures described above, make sure the firearm is not loaded! Also remove the gun handle or stock.
- During all burnishing processes, work in a very ventilated area. The caustic salts used for hot bluing are particularly toxic.
- Do not try hot bluing on aluminum. It will trigger a violent reaction with the caustic salts in the bath, which can cause serious chemical burns.
Things you need
For all proceedings:
- Steel wool
- Sand paper
- Latex or rubber gloves
- Safety glasses
- Chemical cleaners (read in the main guide)
- Lubricating and protective oil for weapons
- Applicators (cotton T-shirts, cotton swabs, swabs, toothpicks, toothbrushes)
For cold bluing:
- Cold bluing solution (commonly selenium dioxide)
- Means for heating the weapon before applying the bluing solution (sun, oven, heat gun, hair dryer)
For hot bluing:
- Caustic salts (usually potassium nitrate and sodium hydroxide)
- Basins, tubs or tanks (for cleaning, burnishing and boiling phases)
- Water (for rinsing and boiling)
- Heat sources
For rust bluing / evaporation:
- Mixture of nitric and hydrochloric acid
- Mix applicator (for rust bluing)
- Lockable locker, large enough to hold gun parts and container with mixture (for evaporative bluing)
- Basins, tubs or tanks (for the cleaning and boiling phases)
- Waterfall
- Brush or roller for carding
