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Gunsmith Blueing / Hot Bluing of Firearms



Q. Can someone give me information on hot bluing of firearm parts so as to get a factory blued finish. Have tried cold bluing but doesn't seem to be as durable as factory bluing jobs. Information on the chemicals needed, temperatures required, tank design etc. How to obtain the difference in color from blue to dark black.

Stephen M [last name deleted for privacy by Editor]
New Zealand


A. From the Chemical Formulary of 1941

Blue-Black Finish on Steel

a. Place object in molten sodium nitrate (700-800 °F) for 2-3 minutes. Remove and allow to cool somewhat; wash in hot water; dry and oil with mineral or Linseed Oil [affil. link to info/product at Rockler].

(Please see our consultants directory for the proper design of the physical plant. There have been many accidents in the improper use of molten salt baths). There are many proprietary solutions for blackening of steel and stainless steel. See our directory of chemical suppliers.

b. Place in following solution for 15 minutes:
Copper sulphate 1/2 oz.
Iron Chloride 1 lb.
Hydrochloric acid 4 oz.
Nitric acid 1/2 oz.
Water 1 gallon

Then allow to dry for several hours; place in above solution again for 15 minutes; remove and dry for 10 hours. Place in boiling water for 1/2 hour; dry and scratch brush very lightly. Oil with mineral or linseed oil and wipe dry.

Gun Metal finish on Brass

The brass is polished, buffed, washed, lightly scoured using water and Pumice [affil. link to info/product on Amazon] , nickel plated, black nickel plated, lightly scoured, again black nickel plated, lightly scoured, rinsed, dried and lacquered. In scouring the black nickel deposit, use a soft steel section wheel and little pumice.

Black nickel plating bath

powdered arsenic 2 oz.
ammonium carbonate 2 oz.
Double nickel salts (nickel ammonium sulfate?) 12 oz.
Aqua ammonia (26%) 32 oz.
water 1 gallon.
Add cyanide to clear.

[Note: J.G. Poor (referenced below) advises against arsenical baths for safety concerns. It is also very difficult to analyze and maintain the components].

From Metal Finishing, 1943, J.G. Poor, Black nickel plating

Sodium sulfocyanide (NaSCN) 2 oz/gal (opg)
Zinc sulfate (7H2O) 5 opg
nickel ammonium sulfate (6H2O) 6 opg
Nickel sulfate 10 opg
nickel anodes.

The black deposit from this bath occurs in a narrow current density range, so racking will become important. It is a thin deposit, but you can rub it with an oily rag to even up the color.

Metal finishing is an art and a science, requires specialized techniques, and is now governed not only by common sense (The layer of prejudices built up before the age of eighteen-A. Einstein), but by statutes designed to conserve public and worker safety. All applicable natural, environmental and safety laws must be obeyed. It is much more effective to find out what these laws are before attempting a job, than to reflect on how easy it would have been to determine them in the aftermath of a workplace accident.

tom pullizzi monitor   tom pullizi signature
Tom Pullizzi
Falls Township, Pennsylvania


A. Steve,

As a part time gunsmith, I can tell you that most people have NO IDEA of how to reblue guns. Most blue jobs require special heated tanks, burners, special salts, and a lot of hard work. Surface preparation of the metal is a key factor because the bluing will enhance any flaws in the metal. Polishing of the metal becomes a prerequisite to a bluing job. Cleaning of the metal with solvents and a thorough degreasing to remove oils and animal fats in the polishing compounds also becomes a key issue.

Most home enthusiasts have neither the time or knowledge to duplicate a professional bluing job. If you must attempt it, contact Brownells [affil. link by editor] for their catalog. These people supply the firearms industry and shooting enthusiasts with parts, tools and bluing equipment and chemicals. They have some pretty good 1 step bluing kits using chemicals called Oxynate #7, Dicropan 1M [affil. link by editor to info/product at Brownells], Oxpho Blue and if you want to attempt a full HOT BLUE NitreBlue.

Be aware of the fact that some of the older side by sides and over unders have only silver solder holding the ribs and barrels together and if you overheat the heated tanks, you could come back to 4 separate pieces instead of a fine old shotgun.

Opt for a cold blue and a lot of elbow grease. It's a lot safer. Leave the hot blue for the pros. You could probably have the job done professionally for about $125 to $175. Probably less than what it would cost you to get the chemicals and equipment together!

Tom S [last name deleted for privacy by Editor]
Reading, Pennsylvania


A. I have been practicing the trade of gunsmithing since 1963.

Unless you have some money and time to spare, have your firearms refinished by a pro. This process takes several years of experience to do right. If you want a detail explanation, I'll be glad to help. Always remember that safety is paramount.

Tommy Burttschell
Master Gunsmith - Pinehurst, Texas


Q. Hot bluing is used by the makers of Lionel trains for years with a high quality finish on tin parts not steel.

I am trying to get similar results with cold bluing with NO success! I will try the Chem. formulas listed here.

Thanks for the recipes / formulas..

Paul B [last name deleted for privacy by Editor]
- Utica, New York


Q. Some years ago I used a solution of potassium nitrate, caustic soda, and distilled water heated to 290 °F, to reblue a colt 1911 pistol. This solution worked well but depends on correct polishing and degreasing of all parts to be blued. Alas I can not find my notes of the exact proportions of ingredients, to obtain the super saturated solution required, can anyone out there shed any light.

Maurice S [last name deleted for privacy by Editor]
London - united kingdom


A. After reading the comment from Maurice, I also used to have a formula for hot bluing. It was sodium hydroxide (caustic soda) and ammonium sulfate, I think. It could have been potassium nitrate. I too, cannot find my notes. I did find the four page "how to", but not the salts needed. This was from a gunsmithing class back in the 60's. The instructor was a graduate from Lassen college gunsmithing school. Anyone know of it. My notes indicate a heating of 275 °F.


CJ Duerksen
Hollister, California

A. Maurice, CJ: If you can find a copy of the Metal Finishing Guidebook from 2000 or earlier, it will have these formulas (the newer editions of the guidebook only talk about how to operate proprietary blackening baths, revealing nothing about home brew).

But the above two posts partially explain what makes hot bluing dangerous. The flash point of water is 212 °F yet these baths operate at 275 - 290 because the solution is so "salty" with caustic soda. Water evaporates very fast at these temps and the evaporation loss must be made good almost constantly. But if a slug of plain water finds itself in a pocket of 275+ solution it can instantly flash to steam literally exploding this 275 degree concentrated caustic onto everyone. Many have been seriously burned and some killed; please be careful and wear full protective gear.

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey


A. You can get this from a druggist to make hot bluing:

spirits of niter 3 drams, tincture of iron 3 drams, sulphur 1 dram, vitriol 2 drams, corrosive sublimate 1 dram, nitric acid 1/2 dram, copperas 1 dram, and distilled water 12 ounces.

However I haven't tried it yet but I hear it works good, but I don't know what temp. to run it at.

Bill R [last name deleted for privacy by Editor]
school - Southern California


thumbs up signBill, have you actually asked your druggist for chemicals like these? 50 years ago most druggists probably could and would sell this to you, but I've lived many different places in the last 35 years and haven't run into a druggist who would sell chemicals to the public. Maybe I've been living in the big city too much.

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey


You may have been able to get this from a druggist when I was a boy, except, what with the American Civil War going on, all this stuff was in short supply.

I doubt that one in one hundred of today's druggists would even be able to give you the chemical formula of these ingredients without having to look it up, but nitric and sulfuric acid (vitriol) are things you won't get from a druggist. They are supposed to help people with their health, not help them to the emergency room.

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Tom Pullizzi
Falls Township, Pennsylvania

"Firearm Blueing and Browning"
by Angier
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Oxynate No. 7

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A. Dear Sirs:

In answer to Stephen M:

I been bluing for many years, with many products and methods , using very different formulas, but at this moment for me the better is Oxynate #7 from Brownells .

Polish the part very well, like an artisan, be patient, and left the part at least 45 minutes in the tank, and please let me know the result, ah, don't forget to read "Gunsmith Kinks" [affil. link to book on Amazon] #1

good luck:

federico quiros
gunsmith - Chicago, Illinois


A. I have a 1952 edition of "General Metals" [affil. link to book on Amazon] by John L. Feirer that has a section on applying a finish to steels. I have not tried any of these (don't know where to get the supplies) and I do not know how well they will work. However for a Black finish: 1 ounce Sulfur [affil. link to info/product on Amazon] in 3 ounces turpentine. Heat solution in a pan of water.; For a Blue color: 2 ounces antimony chloride, 1 ounce gallic acid, and 2 ounces iron chloride in 5 ounces water. ; For a brown color: 1 ounce copper sulfate and 1 ounce sweet spirits in 15 ounces distilled water.

I would appreciate any comments about these formulas.

Dan D [last name deleted for privacy by Editor]
Grand Rapids, Michigan


!! Why do we keep telling folks about formulas that existed years ago? Yes, a lot of them work but only with experience time and money. Mainly experience. I have operated my own shop for 35 years. Before that I was raised in this trade by my father and grandfather. Both of them "Masters" of the trade. Several of the old formulas were used by them, but with the advent of pre-mixed chemicals from several suppliers, all the old remedies could be thrown out the door. Anyone can copy the finish that any mfg. puts on his firearms. All it takes is TIME and MONEY. Each supplier furnishes detailed instructions for their product. Follow them to the letter and you won't be disappointed. Stop and think about this for a minute. If the older formulas were so great then why don't we use them today?

Because what is available on the market is the best that can be purchased. If you aren't willing to spend approximately $1000.00 minimum and many hours of practice, then take your firearm to a professional and have him do it. If anyone would like to respond to these remarks I would enjoy talking to you.

Tommy Burttschell
Master Gunsmith - Pinehurst, Texas

thumbs up signYou get no argument from me, Mr. Burttschell -- I think you are 100 percent right, not only with respect to gun finishing, but all metal finishing. Suppliers started with the century old formulas, then spent decades improving them. And they recover that investment through selling the formulation at a markup.

If people don't wish to pay the markup, or they would rather play with their own formulations, or use what they can find published 50 years ago, that's okay. But they can't realistically expect to find the results of decades of expensive proprietary research for free on the internet.

Still ... many of our readers are from non-Western countries where these Western suppliers are not available to them and they must make their processes from raw commodity chemicals.

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey


thumbs up signI agree with the gentlemen regarding refinishing formulas. I have tried many of them over the years and with the exception of molten salts for straw coloring the new methods are much safer and produce superior results. No matter what product you use the metal preparation phase is the most important. I attended a course years ago and learned that Smith & Wesson feels it take 15 years for someone to become a master polisher. That's doing it every work day, all day!

Mark Stoffel
gunsmith - Suffolk, Virginia


RFQ: I stumbled across this link in search of hot gun-bluing supplies. We are interested in setting up a small scale business in our area after being involved with it with a friend in Florida. There appears to still be a high demand for quality hot bluing, especially at the local level. Many don't wish to ship their firearms out of the area. Many here still believe in contact at the personal level when it comes to goods or services. So, if there is anyone out there that can help us find a web site or information on any companies that offer the supplies to set up for a hot bluing business, please let me know.


Jill S [last name deleted for privacy by Editor]

Ed. note: Sorry, this RFQ is outdated, but technical replies are welcome. No public brand/source suggestions please ( huh? why?)


A. Hello, Jill --

You'll readily find suppliers in our Directory of Equipment or Directory of Chemicals.

The problem isn't in trying to find someone who is interested in selling chemicals and supplies! The problem is in establishing your operation in a way that doesn't terrify them about their potential liability if they do sell you this stuff.

Show them the industrial facility where you'll put the equipment, the protective gear that you will be wearing while doing the bluing, the shelves full of books about the topic, and your 'vanity wall' with certificates from Hazmat training sessions -- and they will be desperate to sell to you. But if ask them to ship it to your home, or you convey the idea that you lack chemistry experience and training, and they'll do whatever they can to avoid selling to you.

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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