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topic 7892

Home Gun bluing -- cold bluing, selenium dioxide

A discussion started in 2000 but continuing through 2018


Q. Hello! Could you help me please? I need a do-it-yourself kind of kit for gun finishing - (the complete process with the chemicals required) Parkerizing or black chromatizing. I want to start this as a hobby because we don't have any access to a gunsmith in my state.

Jonah L Pachuau
- Aizawl, Mizoram, India.

Parkerizing Solution


A. The basic gun finishing process is black oxiding, Jonah. This consists of immersing the cleaned parts into a boiling (about 265 °F) mixture of strong oxidizing salts including sodium hydroxide and nitrites. There are also phosphatizing (parkerizing) processes for moving parts, and cold blackening processes that are safer but not as good. Our FAQ on black oxide and cold blackening is a start. Beyond that, you can search this site for many threads of conversation on the subject. Good luck!

Ted Mooney, Teds signature
Ted Mooney, P.E. - Pine Beach, New Jersey
Striving to live Aloha


Q. I have some black powder handguns I'm bluing with store-bought gun blue (Birchwood-Casey Gun Blue [paid link to product info at Amazon]). It didn't come out as good as I would like, and I noticed the main ingredient is "SELENIUM DIOXIDE". A friend of mine works for an aerospace firm and says he can get me some in powder form. I'm wondering if I can add this to what I bought at the store to juice it up a bit, or do I add it to water or what?

Dan Currie
- YORBA LINDA, California

Birchwood-Casey Gun Bluing


Q. Dan,

I was curious to see how it went. I tried the same bluing from Birchwood-Casey =>
and my job came out black. After contacting B-C directly, they stated that if I wanted to get the bluing BLUE, then send it to the manufacturer I got the barrel from because their formula doesn't blue, it blacks. I have been searching for a "Blue" bluing since. I am in the process for restoring a 1935 8 mm Mauser and want to do the job myself.

Bruce Johnston
- Pontiac, Michigan

Bluing vs. blackening


A. Hi, Bruce. You are more limited in cold bluing than you would be in hot bluing--but hot bluing can be dangerous and complicated. We have an FAQ comparing the two processes.

Something to realize about black vs. blue, however, is that: a matte surface always tends towards black -- because rough surfaces bounce the light around instead of directly back, and because rougher surfaces have more surface area and absorb more dye. A highly polished surface will always look much brighter and a more jewel-like blue with the same bluing/blackening chemistry. See if you can mirror polish something before bluing, and then tell us what happens. Thanks, and good luck!

Ted Mooney, Teds signature
Ted Mooney, P.E. - Pine Beach, New Jersey
Striving to live Aloha

How to make cold bluing solution

"Firearm Blueing and Browning"
by R. H. Angier
from Abe Books
info on Amazon


Q. I wish to know what type of acid is used to make cold blue liquid. I understand it can be DIY by dissolving nails in a acid solution over a period of time. The resulting solution can then be used in place of commercial products. I suspect either citric or nitric acid is used.

Dave Hunter
- Cairns QLD, Australia


A. It sounds like you're being penny wise and pound foolish. Save yourself the headaches (and possible environmental catastrophe) and go to the local gun shop and get a kit to blue your guns. As an FYI, it's the oil over the blackening that makes the gun look blue, and the usual acid is hydrochloric with selenium.

Dan Brewer
chemical process supplier - Gurnee, Illinois

Ed. note: Dan & Ted are on the same wavelength here: whether due to a more polished surface before bluing, or oiling the surface after bluing to smooth it, rough surfaces look blacker and smooth surface look bluer.

To minimize your searching efforts and to offer multiple viewpoints, we've combined some threads into the dialog you're viewing. Please forgive any resultant repetition or failures of chronological order.

Selenium dioxide vs. other cold blacks


Q. Looking to restore the black oxide finish on some specialty German made metric fasteners for a vintage motorcycle project. Although I'd prefer to outsource such work, all the local jobshops aren't interested in running a small batch or used parts for that matter. However, I have found 2 commercially available hobbyist kits that may work. One is a cold bluing kit for firearms, which contains Selenium Dioxide. The other is a cold black oxide coating kit from a automotive restoration supply company, but they will not mention the active chemical.

The questions I have, is cold bluing the same process as cold black oxide coating? If not, will bluing provide the equivalent rust protection as a black oxide finish? Will either of these processes cause any changes in the strength of the fasteners such as Hydrogen embrittlement? Also how safe is it to work with Selenium Dioxide and are there any disposal issues?

Mark [last name deleted for privacy by Editor]
- San Diego, California , USA


A. Soluble selenium compounds are hideously toxic. There are no disposal issues, but wear disposable polyethylene plastic gloves and then wash your hands very thoroughly with soap and hot running water after handling the stuff and taking off the gloves, whether you think you got any on your hands or not. Selenium dioxide based "cold blues" produce a finish that can be patchy and blotchy, and does not wear especially well.

Alternately, you could get the phone book and look for gunsmiths, who, I'm sure, will be only too happy to do the job, and they'll surely use the hot caustic blue process--which wears a lot better than the selenium-based coloring and also tends to look better.

I considered going into the details of doing hot caustic bluing at home here, but the process is not without its dangers (the solution contains high concentrations of caustic strong alkali plus a strong oxidizing agent, and therefore it goes through flesh like a buzzsaw even when it's not at a full rolling boil), so I won't.

John Smith
- Ann Arbor, Michigan, USA

! Your warning on hot caustic bluing is well taken, John, but I personally think the temperature is an even bigger problem than the caustic. Water flashes to steam at 212°F whereas these tanks operate at 265-290 °F and more. One foolish man was having a soda while bluing, dropped the can into the tank, and it exploded -- showering him and causing his death. Other operators have learned that a rumbling sound can mean run for your life: a slug of water is being heated by the tank contents and may be about to blow. These tanks require proper mixing methods so water can be safely added to make good the rapid evaporation losses.


Ted Mooney, Teds signature
Ted Mooney, P.E. - Pine Beach, New Jersey
Striving to live Aloha


A. I've been spending years using all the available products available for bluing guns and gun parts as a hobby. I believe I may have the answer to most problems (HEAT)
I've found lists of comments that this is the secret. It is true. This isn't something you do in a hurry or do without precautions. These chemicals are POISON and I've been careless and have been sick and arthritic curling fingers by not taking the proper safety measures. (Lesson learned).

Birchwood works best. Got to be clean. Preparation by removing rust and blue is not an option, it is amazing how it works. Then comes the trick, propane torch, not too hot but hot enough you'll burn the crap out of yourself if you touch the area (DUUH). When it's clean and hot you can see the color changes in the metal being very careful -- not too hot. Experiment on junk -- very important. Swab the bluing on -- one time , one direction, big or small area let set for 30-40 seconds -- take to sink and rinse it good. Don't wipe. Dry with Clean and dry paper towel lightly use small 0000 steel wool [linked by editor to product info at Rockler] to blend only. Degrease, wipe off and do it all over starting with the torch, over and over. 10-20 times. After the first time you'll say "Jimbo knows his stuff". Very important to use vinyl or rubber Protective Gloves [paid link to product info at Amazon] in all stages. The steel wool sticks into you and hard to pick it out of your skin. Last thing, use a moto tool (Dremel [paid link to product info at Amazon]) with a small buffing wheel and polish like crazy. Don't use any abrasive and do it lightly in full strokes. Be careful because cold blue even with heat is shallow and you may have to get out the torch again. This works and remember is dangerous, (chemicals, torch = danger) Keep chemicals away from torch like remoil, WD-40 [paid link to product info at Amazon] and bluing solutions. The most caustic is the bluing and rust removal. The smell is of HCl = strong acid. Got to get that off everything and it works fast. Try it and let me know.

Jim Howell
- Bacliff, Texas


A. I am getting into hunting for my first this fall, and I was given an old winchester 1200 pump. I love the gun but it was in rough shape, so I stripped the barrel and blued it myself. It took a lot of work and time, but I think it looks very good, no problems what so ever and it has a nice blue when out in the sun.
I simply tore down the gun, sanded the barrel with 220 grit sandpaper, till it was nice and shiny. Then I rinsed it with water, and used a degreaser to remove any oil left. I put on rubber gloves to avoid oil from my fingers and I used Gunslick blue. Put a coat on (be careful it spreads and dries fast), let it dry, then I wash with hot water. It will then look like rust, simply take extra fine steel wool and polish, repeat 7 or 8 times, then let air dry and buff with steel wool and cover with oil, looks brand new.

Todd Moase
- Kensington, P.E.I., Canada

April 11, 2008

A. Just a comment about Cold Bluing. I just refinished a 1938 Large Ring Mauser 8 mm with the step barrel. The original finish was completely gone although only a few minor pits.I sanded it with three grades of automotive wet dry paper. First 400, then 600, then 800 paper. I then degreased using brake cleaner, Acetone [paid link to product info at Amazon] works as well as carb cleaner.

Using an old cotton t-shirt cut up to appropriate size I saturated it with Van's Gun Blue rubbing vigorously as the color got deeper and deeper the more I rubbed. I then wiped it dry with a dry old cotton towel. At this point I rubbed with 0000 steel wool [linked by editor to product info at Rockler] and got the deepest high polished barrel second only to real high grade factory finishes. It was positively better than I ever expected and total time was about two and one half hours. I just finished a Swede 6.5 carbine which I paid $250 and now can expect $600 easily. This Van's is all it's cracked up to be and more. Highly recommended.

Chris Tisch formerly of the Peoples Democratic Socialist Republic of New Jersey. Now safely residing in Arizona where God, Guns and Guts still rule.

Christian Tisch
- Peoria, Arizona

Ed. note: Although your assessment of New Jersey isn't far off the mark, at least we've outlawed shock torture, whereas shock torture devices are Arizona's proudest, and perhaps only, export :-(
Casual digs beget casual digs :-)

Browning vs. bluing

Plum Brown Barrel Finish

August 14, 2008

A. Older muzzle loaders are browned, not blued. A product called plum brown =>
can be bought on line or at your gun dealer. I did a couple of my friends' kit guns and they turned out great. To prepare the metal, I used 0000 steel wool [linked by editor to product info at Rockler], then used the steel wool with liquid soap, dry and de-grease to get rid of any oil -- I use alcohol. You put the parts in the oven so that when you apply the plumb brown it sizzles, do this to the whole piece until it won't sizzle anymore. Wash with your steel wool and soap. Dry -- I use a hair dryer and then oil.

john t [last name deleted for privacy by Editor]
- salinas, California

December 1, 2010

Actually I wanted to respond to a letter written by John T from Salinas, Ca. Normally I wouldn't respond to this type of submission but there is a serious medical concern here. It is alright to heat this product in an oven. One must also bake powder coat in an oven to get the final finish. However, Mr. Thomas failed to mention anything about NOT baking your chemicals in the oven you may very well be cooking tomorrow's turkey dinner in.
You must NEVER use chemicals in your old daily user; if you do YOU CAN DIE FROM IT.

Bill Stevens
- Tucson, Arizona U.S.A.

June 19, 2009

!! I recently came across this line of products called Hoppe's.
It has gun cleaning solvents. They have a product called Gun Blue and I used it to get blue bluing and it worked. I was using this old French pistol and it came out excellent.


Paras s [last name deleted for privacy by Editor]
- Mishawaka, Indiana

Ed. note: We'll be happy to acknowledge otherwise, but we think that, although Hoppe's offers cleaning and gunstock chemicals, they no longer offer bluing chemicals.

March 1, 2012

thumbs up sign I just want to say thanks to Jim Howell and Ted Mooney for the tips that they gave.
I tried Jim's procedure for bluing and it's works very well. The steel has been heated at every layer of blue and it's nice and strong.

Jacques Bolduc
- Matane, Quebec, Canada

Does cold bluing react with silver?

May 30, 2014

Q. I have a steel part with some silver on it. I want to know if cold bluing the will react or change the silver and if so can it easily be buffed off. Thanks!

Tom Shandley
Hobbyist - Bellvue, Colorado

December 6, 2018

Q. What if I need to buy gallons of the stuff to do a non-firearms project. It's really just to temporarily protect the steel from surface rust...and yes, bluing is the best route for this particular application:
1. no need to remove
2. is not a coating
3. is not oily

Nu-Blu offers their bluing in quarts...but I'm thinking 5 gallon pail.
What do you recommend...quality of finish / aesthetics is not an issue.
Does someone out there make an industrial bluing compound?


David Ford
Transportation - Victoria, BC Canada

December 2018

A. Hi David. This particular thread is about cold bluing at home but we have numerous threads about the industrial application of cold bluing as well as hot black oxide processing. When looking for industrial quantities, try googling with the term "black oxide" or "cold blackening" because that's what industrial users usually call the process rather than bluing.

See if you can find a local distributor of metal finishing processes. EPI (Electrochemical Products Inc.) [a supporting advertiser] is one supplier of cold blackening processes.


pic of Ted Mooney
Ted Mooney, P.E. RET - Pine Beach, New Jersey
Striving to live Aloha

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