Rust Bluing

The old Lugers had it. The Mannlicher Schönauers did, too. Most early British high-grade bolt-action rifles and all double rifles had it, as did all British shotguns and quite a few made in the United States. The early Winchester factory employed many old-world craftsmen and my old 1873 Winchester, which I sold long ago to my old friend Ross Seyfried, had it too. I’m talking about rust bluing. The lustre of a proper job of rust bluing, once seen, ruins the discerning eye for all other types of bluing.

Nothing can compare with that look. I’m going to tell you here how I do it and give a few secrets to achieving it—or bungling it—in your own shop. The job is essentially simple but some care must be used along the way. The first step is to get the item to be blued immaculately clean. Once you’ve got all your filing, polishing, engraving, border-lining, or whatever into it, the part will be covered with all kinds of invisible grease. This comes from gun oil, your hands, your cat, and even falls from the sky.

Whatever the source, it’s on there and you’ve got to get it off. One of the best ways is to first wipe the part with a degreaser, such as gasoline or alcohol. (Don’t use your best vodka. Save that for when you bungle the job and have to start entirely over.) This initial wipe-down ought to be followed by using a good metal cleaner like Brownells Dicro- Clean 909. For degreasing longer parts I use a steel boiling tank, obtained awhile back from Brownells, which I used to use for common hot-dip bluing.

This long tank, useful for barrels, barreled actions, and the like, can be placed on two of your kitchen stove’s burners (ask your wife first) to be heated. Suspend the parts in the cleaning solution (or after rusting, in the boiling water) with wires to keep the parts off the bottom, which might contain crud from previous jobs (that really ought not to be there but sometimes is) and also might get the parts too hot from direct contact with the outside metal. For smaller parts I use a dedicated roasting pot.

Don’t handle the parts directly with your bare hands once the metal is thoroughly clean. The next step is to impart very fine-grain rust evenly onto them. That’s the key to making this a simple and repeatable job. In order to do that you need a solution to start the metal rusting evenly and a humid atmosphere to continue it. Rusting Solution In the very old days, stories surfaced of gun barrels being left in the men’s urinal to rust. I don’t think they were true stories but you never know.

The trick is to get the clean steel to start to rust evenly and quickly. The best and fastest initial rust is achieved by a quick wiping with a rag dampened with some arcane mixture of stuff that will "bite" the steel and begin to rust it on contact. The best mixture I’ve used in days of yore was the old Niedner solution consisting of mixing hydrochloric and nitric acids with a quantity of iron nails dissolved in the mix, then diluted somewhat with distilled water.

Back at Mom’s house in southern Michigan I had a friend in the jewelry business and he had these acids on hand. I acquired what I needed and then followed exactly the instructions for making Niedner’s juice. I mixed the acids in the correct proportions, outdoors, in a crockery bowl. Use EXTREME caution or you can lose an eye or a lung! Then I dissolved the correct amount of iron nails (brads bought at the hardware store and degreased in gasoline) No need to find, transport, and mix powerful acids.

Just get a bottle of Classic Rust Blue and have at it. The author has found this compound to work fully as well as the original Niedner mixture he made up and used two decades ago. And why not? It has the same ingredients. That’s the floorplate from his .416 Taylor, about ready for bluing.

My damp-box, a takeoff on a design by John Bivens, is made of scrounged plywood. The front door has four hinges and two simple screen-door catches. The door ought to fit snugly to avoid loss of the generated moisture. The vertical construction allows for placement of long shotgun and rifle barrels for maximum evenness of rusting. Above center: Inside the box we see the heart, which is the controlled-heat pot at the bottom.

This pot, donated by my mother, was a frying or roasting pot with a dial to regulate the heat. I simply fill it with tap water and set the dial to the right spot (learned after lots of testing) to produce water on the verge of, but not actually, boiling. The pot is fitted with a perforated lid, salvaged from a big fruitcake, which keeps the water in the pot and lets the steam out. Note the light bulb. Its cord runs through a hole in the side of the box which allows the bulb to be raised or lowered as needed.

If the box gets cold, or for long sessions that might produce too much moisture, the bulb is a great and fast way to get rid of excess humidity. It heats up the atmosphere which augments the rust process. The bulb cord is hung over a dowel and can be easily adjusted for height. Small parts are put on the shelves, which are loose and have room at back and front for circulation.

Iron wire comes in handy for hanging parts. and then diluted the evil solution the correct amount the correct way with distilled water before putting it to work. Niedner’s solution worked to absolute perfection. With that juice I rust blued my engraved .416 Rigby; my Cogswell & Harrison 20-bore’s barrels; the barrels, trigger guard and top lever of my 12-bore Hollis; all of my famous custom engraved .458 with my fox friend on the floorplate; and my #21 engraved Linebaugh .45 revolver.

I did those all at the old home place in Michigan. Then I moved to Illinois, having taken a job with DBI Books as one of two top editors. I carried the super-juice with me in a brown bottle. At Mundelein I stored that bottle of intense poison away from my cats and dog in the unheated garage, where it froze and broke and went into the ground. Fast forward 23 years and I needed to do some more rust bluing, this time on my .416 Taylor (which I’m engraving) and a few parts from my Westley 10-bore.

Not knowing any local jewelers with supplies of nasty acids, I looked around for alternative rusting juices. I had some stuff I’d used on my percussion Hawken rifle to brown its barrel. It worked okay on the Hawken but didn’t work well

I don’t generally use the small lower shelf but it’s handy if you want to rest a barreled action on it. The tapered plugs are driven into barrels to seal them and used as handles. Smaller plugs like the one on the right are fine for big-bore rifles. I used that one on my engraved .416 Rigby. There’s lots of room for the damp atmosphere to get around the shelf in front and back. when boiled for turning steel blue. What to do? My search led me once again to Brownells. Lo!

They had Niedner’s original formula available all mixed and ready to go. This is their Classic Rust Blue. I got some. It worked. It worked extremely well, in fact. No need to risk life and limb mixing nasty concentrated acids and dissolving hardware-store nails. So now we have a bottle of Brownells Classic Rust Blue and we’ve wiped it very sparingly onto the clean steel to begin the controlled rusting process. What next?

Well, pilgrim, you’ve got to either wait for damp weather to make the parts continue to rust or create a damp environment that you can control and stick the parts in there to continue the rusting process. Back in Michigan I did much of my rust bluing during the winter. Lower-Michigan winters are not known for their high humidity. I needed a damp-box to go along with my original Niedner’s rusting solution.

Humid Atmosphere Some years back a gentleman named John Bivins had a story Far I poked a hole that would accommodate the plug and then closed that large hole off with a simple door. Works like a champ. Here’s the door open. The cord comes out a lot farther, as needed. You can make your damp-box as crude as this one or really do a fine job if you feel the need. I coated everything inside and out with good varnish to keep the wood from absorbing moisture and falling apart.

published in Rifle magazine about making and using a device called a damp-box. (November-December 1974, Rifle, "The Damp-Box"). I built myself one, following Mr. Bivins’ guidelines, out of 3/8" plywood with suitable bracing as needed. I made it a little over five feet tall by a foot square, give or take a bit, with a hinged door and some movable shelves inside. The moisture I bought this roasting pan just for this task. Be sure to keep such things clean and dedicated to bluing.

Don’t cook a chicken in it between jobs. was provided by an electric pot my mother had no more use for. This sizeable vessel holds the water and has a built-in heating element with a thermostat to control the temperature. I fashioned a ventilated top for the pot and placed it in the bottom of my damp box. This device generated controlled Thanks, Mom! After some experimentation I arrived at the correct setting for the heat dial. Then bluing became easy, repeatable, and darned near automatic.

It also keeps parts from falling into the pot. If you can’t find a similar pot to heat water, a tin can on a hot plate with a good thermostat would do. humidity but sometimes the humidity would rise as the temperature dropped, with the result being too much moisture that could settle out as water spots on the cold steel. To fix that I used another trick from Bivins’ old article. I hung a light bulb inside (40 watts, not an LED). This dries and heats the air, and I usually keep the light bulb on during a job.

The light bulb’s cord runs through a small hole in the side and then hangs over the big dowel. Raising or lowering the bulb is thus easy. I make sure I keep its heat away from parts hung or stacked in the box to avoid hot spots on the metal. By being careful, watching closely, and after considerable experimentation I am able to control the atmosphere in the damp box nicely.

I never measured the relative humidity, though it must be close to what Bivins measured in his box: 70-80 percent humidity and with the added heat of the 40watt light bulb, around 80-90 degrees temperature. One needs to experiment with the heat setting on the hot water and with the light bulb’s placement to get the desired very fine rust. The Job So now we’ve got a damp-box and a bit of the nasty fluid that begins the rusting process.

We know how to get the metal clean and how to dampen, not soak, the parts with the bluing solution. How do we proceed? Barrels are hung vertically in the damp-box and small parts go on the top shelf. Typically the parts are left in the humid atmosphere for a few hours, commonly about four.

I used Classic Rust Blue, which is essentially Niedner’s old formula all mixed up for you. Clean the parts, coat them lightly with the Brownells solution and place them in the rusting box. A few hours later take ‘em out and boil them in the small pot. This turns the rust black, as seen here. Let the parts cool and then use something like the pictured #4/0 steel wool, previously degreased in gasoline, to wipe off the dull blackness.

The parts are then coated again with the bluing solution and the process repeated until you get the desired rich black finish. This is somewhat tedious but not at all difficult. They take on at first a light rusting, which ought to be very fine in texture. If it’s too coarse you’ve got either too much humidity or not enough heat in the box. The next step after the rusting session in the box is to boil the parts in distilled water.

At Mom’s place I used water from our well, which was mighty clean and pure, actually the best water I’ve ever experienced. I suggest distilled water, never common tap water. The additives in most tap water will screw up the bluing. This boiling turns the rust black, leaving a soft velvety coating on the steel. That soft, black-turned rust has to be gently removed.

Folks like Bivins and his information source, the Niedner Rifle Corporation, recommended the use of a very fine wire wheel to cut off the surface coating. However, I’ve always used #4/0 steel wool to do that job. The steel wool is, of course, degreased with gasoline before use. Once the parts are all "carded" back to the slightly-darkened steel, the parts are recoated with Classic Rust Blue and placed in the box for another four hours or so. Then boiled, carded, recoated, and rusted again.

The steel color quickly gets darker and eventually arrives at the desired deep, rich, rust-blued look. Shotgun barrels will take on the final blue faster than harder rifle barrels or bolt handles, but be patient and you’ll eventually get what you want. When it’s all done (i.e., when you’re happy with the result), give the part a final boil after the last "carding" but don’t card it again. Oil the part. You’re done. The final result is a bluing job that is unbeatable for beauty and endurance.

Once you try this you’ll never go back to hot-dip bluing, unless you’re forced to do so. If something contaminates the job along the way you might get streaks or spots where the bluing won’t take. Instead of continuing with the process I recommend starting over from clean steel. If you get a horrendous mess for any reason, such as unknown or missed contamination along the way, you may have to redo the job. This means removing all the bluing off down to bare steel again.

Be sure to retain all sharp edges all along the job. That’s one reason I never liked the wire-wheel approach. Even with extreme caution a power tool can easily round a critical sharp corner. Good luck, and don’t give up. I mentioned in my intro that some "gunsmiths" (hardly worthy of the title) have botched this job badly. There are degrees of botch.

One guy I knew in Alaska wanted to get the job done quickly, so instead of using damp air and gentle repeated applications of the rusting agent this fellow used a caustic atmosphere in his damp box and too-strong acid in his mix. The result was that his guns looked blued all right, but had significant, fairly-deep pitting all over all their surfaces. The pitting was even but made the surface of the gun noticeably rough and cheaplooking. Yuck. Rust bluing must not be rushed if you want to achieve a high-quality job.

Be sure to plug any barrels you blue so the rusting solution and the humidity will not enter the bores. I made a set of tapered soft wood plugs for shotgun and rifle barrels. They worked well. This got bluing on the front edges of the barrels but not down inside. The plugs were also convenient handles. I’ve never rust blued a rifle with a tiny barrel, like a .22 LR, so have no experience with how best to plug them. A tapered wood plug would do the job but would not do for a handle.

I’m sure the clever gunsmith can solve that one. As with any new gunny procedure you want to learn, I recommend trying this on junk gun parts before you tackle that old Rigby or ancient Model 70 your uncle gave you. Rust bluing is not a difficult procedure, just a bit picky. It’s extremely satisfying when you get it just right.

One further tip: If you want the best look on screw heads and other tiny parts, polish ‘em to bright steel and then heat-blue them to a lovely deep blue with a propane torch, a handy water container to stop the process instantly, and a little skill. Good luck. AG