How to hot blue, for those that want to know

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g17

Bearcat
Joined
Sep 6, 2007
Messages
14
Location
KY
I've read many articles on various gun forums regarding gun bluing, most often cold bluing but seldom any information on how to properly hot blue. I'll share this information for those that would have a notion they might like to attempt this at some time. Please remember safety and never attempt mixing salts indoors unless you have some extremely good ventilation. Also remember that you should not do this unless you are competent in fully disassembling the firearm to be blued. NEVER PLACE AN ALUMINIUM PART IN BLUING SALTS. Also, post 64 Winchester lever action receivers will not blue without a special activator.

The process is not as difficult as it may sound and with practice, can be done exceptionally well without a lot of equipment costs. The key to any bluing job is the polishing done prior to it being blued or if you prefer a matte finish, it is bead blasted prior to bluing. Preferably, practice using a gun that isn't worth a lot.

Equipment needed:

USE EYE PROTECTION AT ALL TIMES

Of course you can purchase pre-mixed salts or you can do as myself, make your own. The following recipe is as, if not more, durable than any mfg that I have tried and the color is what you would typically find on older higher end pistols/revolvers.

USE EYE PROTECTION AT ALL TIMES

Salt recipe: 1)Sodium Hydroxide (e.g. lye, caustic soda) can be bought at any chemical supply and some cleaning supply houses. 2) Ammonium nitrate which you can buy at most farm supplies. 3) Distilled water. The mixture is 2:1 sodium hydroxide/ammonia nitrate. For small tanks/pans, 2lbs/1lbs mixture should do it and in a standard long tank, 5lbs/2.5lbs will do. When the two are first mixed and just enough distilled water added to moisten the chemicals, there will be an extreme chemical reaction reaching boiling temp and creating a very powerful ammonia smell that will subside within about 5-10 minutes. However, it is IMPORTANT that when first mixing, you do this outside in a very well ventilated area. After the reaction occurs, the salts will cool and the fumes will be minimum and you then add more distilled water until you have about 2" of water above the salts.

This solution can be used numerous times. Just keep it covered when not in use

Metal (Steel, NOT CAST IRON OR ALUMINIUM) pans large and deep enough to completely submerge part in leaving about 2" from top of pan. For long gun barrels, etc, a bluing tank can be purchased from brownells for reasonable cost. I've used commercial grade stainless steel rectangle shaped pans like you find on a food serving line and they work as good as any and have a nice lip all the way around.

metal wire for suspending parts and small baskets made from steel window screen to place screws etc in.

A heat source that you can control the amount of heat. Gas burner(s) or electric hot plate, old stove, etc

Thermometer that will register to at least 300*f. A good cheap method is to buy a glass candy thermometer.

gloves

4x steel wool

Dawn dishwashing detergent.

WD-40 or the cheap Wal-Mart brand will work fine.

Aluminium Oxide automotive grade sand paper in various grits up to 1000 grit.

The process:

After disassembly of the weapon to be blued, place all parts such as springs and aluminium parts into a container (zip lock will work) and put aside.

Polishing. Here is where patience comes in. The best bluing jobs are and always will be hand polished. If you choose to do this with a buffing wheel (not to be confused with what you would find on a Dremel tool), I use Felt Wheels (Brownells) and have never seen anything much better than utility grade jobs coming from Muslin wheels. Also, if you use wheels, avoid the lettering, screw/pin holes and sharp edges on the piece being polished. Here's what I recommend. Depending on the condition on the metal, start with coarse Aluminium Oxide paper in the 100 range. Using wood or padded blocks, place the piece in a vice snug enough to hold it, using a shoe shine method, begin polishing the rounds (barrels, top of frame/slide, etc) until it is uniform. Depending on the condition of the metal, you may notice what looks like fine black marks/pits in the metal. If so, continue polishing until the steel is uniform and free of imperfection. Progressively work up using finer grits of paper to polish. When you get to the 500 grit range, you can stop as the finish will at least rival anything on what was once seen on older S&W's. For Python like finish, work up to 1000 grit. For just a good looking finish, stopping in the 300 grit range will be superior to most any weapon sold on the market today.

For the flats, I use a flat table and a smooth marble 18"x18" tile. Lay the paper on the tile and work the piece across the paper keeping it flush and progress to the grit paper you desire.

For a matte finish, plug all chambers and barrel (I use spent cases in the chambers and lead bullets to tap into the ends of barrels: remove before placing in bluing) and use a good grade of masking tape to cover any areas you do not wish to matte. Blast with a fine grade of glass bead until uniform.

Bluing: ALWAYS USE EYE PROTECTION & DO NOT PLACE ALUMINIUM IN SOLUTION, IT WILL DESTROY IT. Keep distilled water handy and add to mixture as needed for evaporation loss. Add it between batches and let solution get back to proper temp before continuing.

Heat needs to be constant. Going above 315*f, 310*f on some, will almost always result in "exotic colors" such as the often seen purple (plum), reds, and greens.

Heat bluing salts to 295*-305*f, stir the mixture with a steel ladel to insure heat is continuous throughout solution. Suspend piece(s) completely submerged in tank for 20 minutes. Remove and place in a pan of water. Using 4X steel wool and dawn detergent, scrub piece completely, examine and if it isn't perfect, rinse and place back in solution for another 20 minutes and clean again with steel wool. After scrubing and the peice is satisfactory, spray with a heavy coat of WD-40, set aside and finish other parts. When finished, for best results, boil all parts in clean water with 1/2 cup baking soda per gallon of water (I know both baking soda and sodium hydroxide are bases, but it works) and while rinsing, use a toothbrush in any crevis. Dry and spray/wipe down with a quality lube, Breakfree CLP works fine. Re-assemble your weapon.
 

two bit okie

Single-Sixer
Joined
Dec 27, 2004
Messages
220
Location
Topock, AZ
for those who might try this, I ran it past my son. A college boy with knowledge about chemistry. He liked to had a heart attack. Dangerous fumes can kill you. High temps can burn the bejesus out of you. Best if you can find a chemical plant tank cover.

All which are covered in the article.

JUST BE VERY DAMN CAREFUL AND KEEP AWAY FROM THE GOOD STUFF, AND OUT OF DOORS.
 

Geri

Bearcat
Joined
Sep 15, 2006
Messages
74
Location
Wheatland WY
I usually use a chemical mask when blueing. The mix for the salts you mention can be found in Roy Dunlaps book on gunsmithing. It gives the hardest surface finish I have ever used. One thing, depending on the elevation that you are blueing at, you may need to start at a lower temp. 285 degrees F. When I started blueing my father-in-law was a chemical engineer. One of my daughters has a masters in chemical engineering, and works for ATK. I have had a lot of input on blueing over the years. Brownells has good information also.
 

Luckyducker

Single-Sixer
Joined
Nov 18, 2007
Messages
199
Location
Ft. Morgan, CO
I realize there is no such thing as a stupid question just stupid people, but should a rifle be blued with the barrel attached or removed? :?
 

g17

Bearcat
Joined
Sep 6, 2007
Messages
14
Location
KY
if it is a barreled action, e.g. barrel screwd to the receiver, blue it it as one piece. Make sure you clean it well afterwards and pay attention over the next week or so to where the barrel fits to the receiver to make sure no bluing creep developes. If it does, wipe it off, keep oiled, and no harm done.
 

Tx gun runner

Single-Sixer
Joined
Mar 18, 2007
Messages
264
Location
Ft Hood , Tx area
WEAR GOGGLES OR SHIELD . TWO FRIENDS BOTH LOSS SIGHT IN ONE OF THERE EYES FROM BLUEING.. THERE NO FLUSHING IT OUT ONCE IT HITS YOUR EYE YOUR DONE
 
Joined
Nov 3, 2007
Messages
481
Location
Douglas, AZ, USA
Doesn't placing gun parts in such high temperatures run the risk of damaging the tolerances of the metal? I once bought a do-it-yourself parkerizing kit and parkerized a 1911 slide. When I was done and put it back together the slide fit sloppy - ruined it! this was only in boiling water temperatures! I have a Blackhawk I want to blue and was thinking of trying this recipe, but I'm afraid to ruin it!
 

g17

Bearcat
Joined
Sep 6, 2007
Messages
14
Location
KY
Temper isn't usually affected until at least 800*. When nitre bluing (fire blue), it is limited to non-stressed parts as the temp will meet or exceed 800* to get a brilliant blue. Not sure what happened with your adventure, maybe the gun was cleaner than it had been or was bead blasted improperly prior to being parkerized........your guess is good as mine but I do know that the steel in a 1911 isn't going to be affected by parkerizing temps (usually done around 180*). I've parkerized 100's of 1911's and never had an issue.
 

Denver Express

Bearcat
Joined
Apr 20, 2005
Messages
2
Location
MI
FWIW to anyone who may be thinking about trying this , I went recently to the farm CoOp to see if I could buy some ammonium nitrate fertilizer. The lady behind the counter looked at me as if I had two heads when I asked if they had any I could buy. Almost the first thing out of her mouth was "you know that's what they use to make bombs don't you?"
I assured her that wasn't what I wanted it for and further befuddled her by trying to explain what I did intend to do with it.
Anyway,she said they didn't have it and with the paperwork involved, no one bothers with it any more.

Take care, Ron
 

RugerMarkIII

Bearcat
Joined
Dec 3, 2007
Messages
7
As a chemist, I must strongly advise against the OP procedure. It is NEVER a good thing to have all of your starting materials "react at once" to create an "EXTREME" reaction that reaches boiling temps. Just my .02.
 
Joined
Dec 11, 2002
Messages
8,966
Location
Ohio , U.S.A.
I think you'll find that oil alone does not 'neutralize' the salts, any parts that are threaded together and blued ,together, needs to be "boiled" out ( hot water bath/rinse...........) to keep it from "bleeding".........
placing a barreled action into the hot tanks is a very awkward and dangerous proposition...must angle it and do this facing "away" from you, as it can and will shoot 'solution' ( bath) out the open, upper end....seen it happen MANY times..........\

as for the slide on a 1911 warping from the temperature of a 'salt bath' or better yet any parkerizing bath, I find hard to belive that to have happened.......but, who knows what the metal was "exposed" to BEFORE....
 

dwade7551

Bearcat
Joined
Mar 13, 2009
Messages
1
I have used this formula for many years. I use a 50 cal ammo can for handguns. It works beautifully, you just need to be careful and use common sense. The chemicals do get hot when mixed but the reaction is not extreme, or violent. The is no explosion or sputtering. If you mix the water and lye first it will get hot. You then add the nitrate, either ammonium or potassium (stump remover) if you can't get the ammonium. I heat it up over one of those gas burners they sell for turkey fryers outside.

I have parkerized quite a few slides on the kitchen stove, the temp doesn't even get to boiling temp. Around 180 degrees if memory serves me right. I don't see how a slide could be ruined by the parkerizing process unless maybe you fell asleep and left it overnight. But even then I think the process is self limited, just like bluing is.
 

I_Like_Pie

Blackhawk
Joined
Aug 24, 2006
Messages
659
Location
Chattanooga, TN
I agree that the garden people look at you funy when you ask for ammonium nitrate...rarely are they versed on uses other than growing and destroying things with it. If you can not find the ammonium nitrate you can go to Walmart and buy instant cold compresses for $1 each...each bag has 0.368 pounds of ammonium nitrate in it.

$10-12 for enough in the large batch mentioned above
$5-6 for the small batch.

Drain crystals (such as draino) are 100% lye...this is about the same price as the ammonium nitrate.

This is relatively expensive for such common chemicals, but for under $30 you have all you need to do a LOT of bluing. Whenever we make a batch we have a bunch of people prepare their stuff beforehand and do 5 or 6 guns, couple of pistols and a couple of buckets of bolts and parts that were boogered up while tinkering. You can use an iron pipe welded up and slotted on the top + a propane camp burner for the heat. Just make sure it is sturdy and will not spill anywhere.

THESE CHEMICALS WILL HURT YOU VERY SERIOUSLY IF YOU ARE NOT CAREFUL. If you have the slightest inkling that this type of work is over you head...don't bother with it.
 

I_Like_Pie

Blackhawk
Joined
Aug 24, 2006
Messages
659
Location
Chattanooga, TN
I have to add this as I find it rather funny. According to the MSDS for Drano crystals

---------------
CLICK HERE
---------------

They are 60% Sodium Hydroxide and about 30% Sodium Nitrate. This is almost exactly the proper ratio of chemicals for several bluing recipies that I have found. I think that I might give that a try on some tools in the basement to see if it works...It just might.
 

curtisaurus

Bearcat
Joined
Feb 12, 2009
Messages
2
Location
Virginia
I_Like_Pie":jcacrj4h said:
I have to add this as I find it rather funny. According to the MSDS for Drano crystals

---------------
CLICK HERE
---------------

They are 60% Sodium Hydroxide and about 30% Sodium Nitrate. This is almost exactly the proper ratio of chemicals for several bluing recipies that I have found. I think that I might give that a try on some tools in the basement to see if it works...It just might.

Old thread I know... but how did that turn out if you ever tried it? :)
 

Denny Crane

Bearcat
Joined
Mar 12, 2010
Messages
8
Location
NE KS
I am going to give this mixture a try. Just a small amount to experiment with until I am confident enough to try it with any real parts.

I have to ask? How do you heat the liquid to 295 deg in an open container? The chemicals will alter the boiling point but I doubt it is even close to 295 deg?

No matter how much heat is applied if no pressure is present it should just boil/evaporate, making it impossible to heat the liquid to 295 deg?

Your experience??

Thanks
 

Denny Crane

Bearcat
Joined
Mar 12, 2010
Messages
8
Location
NE KS
I figured out how to get it to 295 deg. On my first try I added too much water so the next batch I mixed up I only added enough water to dissolve the chemicals. It still took a little while but as the water boils off the temp of the solution increases.

It worked great with one exception, the first few parts I have blued are not a blue/black as I would like. They have a very slight brownish color? The finish is nice and seems very durable, certainly better than any cold blue I have used.

Any ideas how to get more of a blue/black?

Thanks
 

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