The DIY Rust Blue
I’ve reached a conclusion about rust bluing. It’s mostly superstition, with a few facts tossed in as a distraction. Practically everything I’ve read on it made it sound like a complicated, difficult and mysterious process. However, here are some hard facts and techniques on the rust bluing method:
First, you have to know the chemicals used for the processes, and the humidity and the quality of water you’ll be working with. Such facts are fairly well settled, since they’ve been in use for a few hundred years. Today, instead of rainwater, the use of distilled water ensures the desired consistent, repeatable results with no surprises. Judging weather and application technique is mostly superstition, although a home weather station takes some of the mystery out of humidity.
Second, you have to know the type of steel you’re working with.
Practically all carbon steel will rust, but stainless steel won’t. Softer steel—often used for buttplates and triggerguards—can finish before the barrel or barreled action. Continuing the acid treatment may begin to etch those parts before the others are finished. Degreasing thoroughly is paramount. Get all the oil off the steel.
The only major purchase involved is a water tank big enough to hold a barreled action and a method to boil the water. Brownells has both at a reasonable price. The set up I use runs off a standard BBQ propane tank. Brownells sells rust blue solutions, too, or you can mix your own. I once mixed my own, but don’t anymore. I’ve been using Pilkington’s American Rust Blue solution for more than 20 years now with good results. It works so well I haven’t switched (yes, I’m superstitious).
Pilkington’s solution will give you good results on the first try if you follow the instructions carefully. His instruction booklet is clearly written and the first one I read that gave me the confidence to think I could rust blue successfully.
After you have a couple of jobs under your belt, you’ll begin to see ways to do the task your way—which is where you begin to form your own superstitions!
I get pretty good results using nothing more complicated than files, stones and aluminum oxide wet/dry sandpaper for polishing and steel wool for “carding” off the rust, with a minor assist from a soft wire hand brush. Most directions say to polish to 320 grit, which is fine as long as you get the scratches out, or blended in the right direction. If you don’t, the scratches will enlarge as the acid etches them. These days I polish to 600 grit. At the higher polish, I sacrifice some depth of color for the sheen the high polish gives.
This Krag sporter was polished to 320-grit and only three long passes of the solution were used to give it a soft matte gray finish. The safety and extractor were heat blued on the stove using a cast iron pan. (Heat bluing in this fashion is time consuming, but inexpensive.)
Since the acid etches the metal, it would seem counterintuitive to give the parts a high polish, but I don’t leave the barrel under the acid as long before boiling and carding—how long the metal stays under the acid affects the final look. Since the humidity is low where I live, I let the steel rust for four hours in the first four passes, and I can do two passes a day. In areas with higher humidity, I’d follow Pilkington’s instructions of three-hour passes. Then I go to six hours of rusting until I get the color I desire (it only takes one or two more passes). It takes about five minutes to apply the acid to the barrel, maybe 15 minutes if a lot of other smaller parts are blued, so I can get a lot of other work done while the parts rust.
The blue is accomplished by applying the acid-based formula (typically a solution of nitric acid, hydrochloric acid with iron dissolved in it and diluted with water), allowing red rust to form on the steel, then submerging it in boiling distilled water for 10 minutes to convert the red oxide to black oxide and carding the surface “velvet” off.
Most instructions call for the use of power equipment to card the rust. I don’t use it. Since I’m doing this for myself—not as a business—working around my lack of power equipment isn’t too arduous, but it does take a little more time. I use 0000 steel wool (factory coated with an oil preservative) degreased in hot, soapy water and dried with paper towels. Birchwood Casey Gun Scrubber works well to degrease the steel wool, too. I spray it over paper towels so the oil is soaked up.
Most instructions insist you wear gloves to keep from contaminating the barrel. If any oil gets on the steel during the application of acid, it will not rust in that spot. I wear nitrile gloves to apply the acid, but not to card. After carding, I clean the bore and barrel with mineral spirits (I use mineral spirits and Gun Scrubber to degrease the parts initially as well). This removes any fingerprints or oil left by the steel wool if it wasn’t completely degreased. Running a patch wet with mineral spirits down the bore keeps the inside of the barrel from rusting. This is important because the bore isn’t going to have any other protection for several days.
Jeff’s first effort at rust bluing a barrel was on this Ballard No. 5 Pacific (above). It turned out poorly (he didn’t boil it long enough), and he had to repolish and do it all over again to 400 grit, which gives it a matte finish. The Remington-Gove underlever
(below) was polished to a higher 600-grit for a much more pleasing finish.
I keep plenty of wooden dowels which loosely fit the bore (too close a fit and the water will swell them tightly in the barrel) and place a dry one in the barrel while the acid works. I use a broomhandle with soft iron wire hangers on it to suspend the barrel on the dowels in the water. As I lift it out of the water, I use a hair dryer to blow the water off the barrel and parts, especially around dovetails. Any water allowed to puddle will create a spot as it evaporates, and the barrel will be hot enough to evaporate the water very quickly. In fact, the water will evaporate so fast it must be blown off as the barrel as it is (literally) rising from the water. I lift it on an angle so I can blow out one dovetail at a time. Even this must be done quickly.
Brownells offers inexpensive soft iron wire. It is very useful for suspending small parts or run through the barrel of smallbore rifles, since dowels smaller than .38 caliber often aren’t strong enough to support the barrel. I also use a retired stainless steel cleaning rod through the barrel. Just make sure it has no oil on it either! Any oil in the water can spot the blue upon removal. Oil floats, so get it off the surface with a paper towel if you see any.
The fixtures I use to suspend the parts while the rusting occurs are just knocked together from scrap wood. The fixtures differ slightly depending on the parts to be suspended, and how I want them suspended while applying the rust. Being able to turn them without touching them is a big help.
When I lived in Southern California, I found rust bluing wasn’t hard in the summertime, but I had a brand new learning curve here in Northern Nevada where the air is much drier. Humidity is necessary for the acid to create rust. I managed to accomplish the Wesson No. 1 barrel without the use of a “sweat box” to maintain consistent humidity, but getting one is on my to-do list.
Try not to touch the metal if at all possible during the process, as the blue is tender and will show handling marks. When I’m satisfied with things, I allow the barrel to sit overnight with nothing on it. The next day, I coat everything generously with Rig and leave it on until assembly. Don’t use a rust removing oil! It will try and remove the blue and ruin all your hard work.
John King and Jeff collaborated on this Wesson No. 1 in .45-90 Sharps on a Steve Earle action with a 34-inch Krieger barrel. It is Jeff’s first bluing effort here in Northern Nevada. Mike Gouse engraved the action and barrel.
Brownells’ tank, stand and LP gas burner is pretty much a turnkey operation for rust bluing. Add a propane tank and a hose and you’re up and running.
In all, the one-time cost for the tank, stand and LP burner are around $500 or so. Rust bluing handguns is even cheaper yet, since you only need a pot big enough to submerge the handgun completely in boiling water on a stove (with the little lady’s permission, of course). The store-bought chemicals are relatively long lived, and you’ll use small amounts per job.
The beautiful silky blue is its own reward, and a gift you give yourself. If you make a mistake, be prepared to repolish and try again (yup, done that—twice, so far). My first successful job was on a 1917 Enfield triggerguard done in an old turkey roaster some 30 years ago. My second was a 1911. I did both with homemade solutions. I only do a one or two pieces a year, but the results have been well worth it. They’ve allowed me to aspire to more highly finished arms than I can otherwise afford.
I purposely left out “in progress” photos. Frankly, the parts just look like blobs of, well, rusting metal. My goal is to inspire you to try by showing the finished product. I was too intimidated to try for a long time, because a lot of the stories I read on rust bluing made it seem more like voodoo than work.
What sealed the “do it yourself” deal for me was the high cost and long wait times involved in having rust bluing done at a shop. I know many GUNS readers have the attention to detail to give it a try and do as well.
By Jeff John
Brownells
200 South Front Street
Montezuma, IA 50171
(641) 623-4000
