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Bluing The Traditional, Hot Salts Way

My trusty Remington 870 has been through a lot here at Brownells since I purchased it. I have disassembled, bead-blasted, cold blued, reassembled, and disassembled again . . . more than any shotgun often goes through in a lifetime of use. And, having heard a lot about Bob Brownell starting this great company offering hot salts bluing products, I thought now would be a great time to see how the traditional, hot bluing salts method is done, and how it compares to some of the other finishes I’ve been working with this past year. I figured I’d get an almost “factory-new” look to my shotgun – and this month’s WebBench™ article completed at the same time.

That’s when I spoke to one of our gunsmith techs here, David Bennetts, and asked him what it would involve to re-blue my shotgun. He looked me in the eye, and said, “You are going to get an education.” We decided to fire up the bluing tanks on an unusually cool Iowa August day, and he would give me my education in the art of hot salts bluing.

Before the advent of the modern solutions for bluing guns, giving a firearm that unique, blue-black finish was an exhaustive procedure requiring many, MANY hours of intense, hands-on labor. The gunsmith owes a debt of gratitude to Bob Brownell, who revolutionized bluing with the introduction of Oxynate No. 7. This solution allows the gunsmith to blue a greater number of guns with significantly less work. Most importantly, the bluing process is repeatable with consistent results that will make the gunsmith confident in the work they are doing. The blued finish is relatively simple and easy to achieve. It involves seven basic steps:

1.Clean the properly polished gun and parts in Dicro-Clean 909™.
2.Rinse and scrub in cold, clean water.
3.Immerse in Oxynate No. 7 solution for 15 to 30 minutes.
4.Rinse and scrub in cold, clean water.
5.Rinse in boiling water.
6.Immerse in Water Displacing Oil.
7.Apply optional “after-treatments”, if desired.

David and I started our bluing training with some safety precautions. Hot bluing salts are very caustic and must be handled with caution. Proper ventilation, eye protection, skin protection and fire protection are NOT optional. They are absolute necessities and CANNOT be overlooked. Read the directions booklet that comes with the pail of Oxynate No. 7 carefully and make sure you understand everything before you begin. If you have any questions, do not hesitate to contact the Technical Support Staff at Brownells.

After reviewing and following the safety procedures, we began by stirring the tank containing the Oxynate No. 7. It is important to break up the surface salts and the material that has settled to the bottom of the tank. Once this was done, David lit the burners on the Brownells Bluing System for the Dicro-Clean 909 tank, the Oxynate No. 7 tank, and the boiling water rinse tank.

As we waited for the tanks to heat to the proper temperature, David told me that, in his opinion, bluing is one of the more profitable areas of gunsmithing. As we looked at the parts of six guns that were to be blued (our co-workers found out what we were doing and chipped in to add to our workload), he suggested that what we were looking at represented about $400-500 worth of work. It seemed to me that one could make up the cost of the bluing equipment in a relatively short time. David confirmed this by saying that once people find out you can blue a gun and do a great job, they will “beat a path to your door.”

The Brownells bluing room utilizes the full Bluing System Kit. For those of you who might not have a lot of room and still want to blue your own parts, you might consider the Brownells Roll-Around Compact Bluing System which will handle up to 18” barrels and rolls out of the way when you’re not using it.

Once the tanks reached the proper temperatures, we were ready to begin. The parts to be blued had been cleaned and polished beforehand.

We first ran soft iron wire down the length of the barrels and through holes in the parts with enough wire protruding to hang the parts on the hanging rods across the tanks. This makes it easy to move the parts from one tank to the next without touching them. You also won’t need to worry about any contamination from the wire since that also goes through the entire cleaning process.

The next step was cleaning the polished parts in the tank of Dicro-Clean 909. This tank heats to 180° F and is used to get the parts absolutely free of any oils, dirt and grease. Get the part clean! Any trace materials will botch up the bluing. Parts should be immersed and scrubbed for 10-15 minutes.
Once this step was completed, we rinsed the parts in cold, flowing water to remove any traces of the Dicro-Clean 909. This should be done quickly, taking no more than 2-3 minutes. Any Dicro-Clean 909 left on the metal will cause the bluing to streak.

The part was then put into the Oxynate No. 7 Bluing Tank, which was boiling at a temperature of 292° F. It is important to make sure that no air is trapped inside a barrel or part when it is immersed in the bluing tank. The hot temperature will cause the air to expand rapidly and will blow the caustic solution all over you and the shop. Tip the part up as you lower it into the tank, making sure that no air is trapped inside.


The part needs to be in the bluing tank for 15-30 minutes. When using a stainless steel basket to hold small parts, make sure that you swirl the basket around slightly to ensure that the parts are completely coated. It is critical to completely cover the parts being blued with the solution to prevent any discoloration or uneven bluing.

At this point, an assembly line procedure can be started, with parts being cleaned as you wait for the bluing solution to work its magic. Watch the temperature on the bluing tank and make sure that water is not boiling off, which will improperly balance the mixture. The instructions for the bluing system give you tips to properly maintain the solution balance. Read and follow them carefully.

Avoid leaning over the bluing tank as catching a face full of vapors is a very undesirable feeling. After 15 minutes, check the part by briefly lifting it out of the bluing tank. Rust will attack the metal quickly, so take a quick peek to see if the desired color has been attained.

Once you are satisfied with the color, rinse the part in the cold water tank. Agitate and swish the parts in the water to remove all traces of the bluing solution. Then place it in the Boiling Water Tank for 5-10 minutes for simple parts, or 15-30 minutes for complex parts, to boil out any remaining salts residue.


David gave me a great tech tip. When you remove the part from the hot water rinse tank, apply Brownells Solder Black on any soldered joints. David used a cotton swab to apply the Solder Black and it turned those solder areas black to match the blued steel. Applying the Solder Black at this time is ideal because the metal is perfectly clean and hot which allows the Solder Black to work quickly and give an even finish.

After removing the parts from the hot water rinse, they were placed in the Water Displacing Oil Tank. This removed any water from the part, and gave the metal a protective coating to prevent rust, sweat, or body oils from disturbing the finish. The parts should remain in the oil until they are cool, usually 45-60 minutes. This will allow the maximum displacement of any trapped water.

That was it! We had blued the parts for six guns in about 3 hours from the time we fired up the tanks until we took the last part out of the oil. The result was a deep blue-black finish that was consistent and even, without any discolored areas. It was a relatively easy thing to do, despite the occasional itching from the steam from the bluing solution. That was a small price to pay compared to the satisfaction I felt from taking my 870 from bead-blasted steel to a professional-looking blued finish.

As David and I talked, it became apparent that with practice and attention to detail, bluing was a job that can generate a lot of business for the gunsmith. The initial investment is not overwhelming, and the results were professional, even for this novice. The instructions provided with the bluing system, along with the technical support from Brownells that is only a phone call away, can let you provide a service for your customers that will leave them very satisfied – so satisfied that word-of-mouth can lead to a very profitable and satisfying part of your shop's income.


Many thanks to David Bennetts, Gunsmith Technician . . . just one of the many qualified Gunsmith Technicians here at Brownells.

Materials Used
Brownells Bluing System Kit - #082-005-007
Brownells Solder Black - #083-032-004
Brownells Cotton Swabs - #080-000-255

Alternate Materials
Brownells Roll-Around Compact Bluing System – #082-900-008