Nitre Bluing

Once again, this is a collection of posts C&P from another forum which spanned several months.

In my research into restoring the Krag, I have found that Springfield Armory used several different metal finishes for the various parts of the rifle. Many of these finishes were a byproduct of that parts manufacturing process.
The bluing of metal is an oxidation process. It can be achieved in several ways.
One of these is Nitre bluing. It was used as a tempering process to draw back parts that had been case hardened, and it was used as a final finish on parts that would not see pressure.
As with other 19th Century technology, it is fairly easy to do for the advanced tinkerer.

Here's some pics of my first attempt at Nitre bluing.

Salts heating up.
https://www.milsurps.com/images/impo...f441246c-1.jpg

Some parts from my junk bin that will serve as test pieces.
https://www.milsurps.com/images/impo...6350c9a7-1.jpg


Part in salt bath.
https://www.milsurps.com/images/impo...21457943-1.jpg

Before, after polishing, after bluing.
https://www.milsurps.com/images/impo...28734cb6-1.jpg

I had intended to do one of the barrel bands pictured. While in the bath, a thunder storm came up. Needless to say, water in a 800F salt bath is bad news, so I had to shut down for the day. Maybe tomorrow.

The range of colors possible by this process is determined by the temperature and immersion time. Straw colors as seen on Luger triggers, as well as the peacock blue used on screws and pins on 19th Century arms are possible.

With all the rain we've been getting, It's taken til now to get some time to play with this further.
Polished up another swivel from the pile of Krag parts. Heated up the salts to 650* to have a stab at getting the peacock blue color. The salts are hydroscopic and had absorbed a bunch of water when it rained me out the last time. Had to let the pot simmer and boil off the water before cranking up the heat.
Polished the swivel up til it looked like chrome.
https://www.milsurps.com/images/impo...593f3667-1.jpg

At this temp, the color changes come slower and it's easier to get the color you want without it slipping by you. This is what it looked like after quenching. It took between 2-3 minutes to turn this color.
https://www.milsurps.com/images/impo...482448b8-1.jpg

I dried it with compressed air and oiled it. It immediately darkened. Still blue, just dark blue. Then I remembered reading that you should let the part sit overnight before oiling.
https://www.milsurps.com/images/impo...1f0162a9-1.jpg

A friend was here the other day and I was showing him some of the small parts I had nitre blued for the Krag project. I mentioned that all but one of the screw heads had slot damage from using the improper screw driver and I had repaired the heads prior to bluing. He said, "How do you repair a screw"?
That made me think that this may be something some of you might be interested in.
Everybody's seen them. The boogered screw heads that someone ruined by not using the proper screw driver. Well, the Krag had plenty of them. As a matter of fact, only one screw escaped Primitive Pete and his heavy handed use of a screw driver better suited to opening cans of paint and serving as a makeshift chisel.

Anyway, most screws damaged in this fashion can be salvaged and cold blued if the gun is not being refinished.
You take the damaged screw and secure it in a vise so that the head of the screw is supported by the jaws of the vise. Then take a smooth faced ball peen hammer and peen the raised metal back down into the slot. If the screw is very badly damaged, you may need to use a punch to take care of a small spot, but a hammer is usually sufficient. Do not use the claw hammer with the pock marked face you use to drive tomato stakes for the wife. You want a nice smooth face on the hammer that will not make things worse. Tap, do not pound on the screw.

This was the worst screw I had to deal with on the Krag.
Now some of you may say, why don't you just order another screw. Well, when you're dealing with a 112 year old rifle, the rest of the screws out there are likely in the same shape as yours, so if you spend $3 for a screw from Gunparts plus $5 shipping, you may end up with another boogered screw just like the one you already have.
https://www.milsurps.com/images/impo...d530a705-1.jpg


After you have peened the screw, use a flat needle file to recut the slot so it's parallel.
https://www.milsurps.com/images/impo...3d98f131-1.jpg

This screw was so badly damaged I couldn't get it perfect, but it's not too bad. This is after polishing.
https://www.milsurps.com/images/impo...86d30cff-1.jpg

Here are the other screws that were repaired. This is after bluing in the nitre salts.
https://www.milsurps.com/images/impo...d6198c33-1.jpg

I also did the rear sling swivel at the same time.
https://www.milsurps.com/images/impo...bf5eef3a-1.jpg

Finally got a good day to set up and finish bluing the Krag parts. Now all that's left is to rust blue the barrel, action, and load gate and side cover. And finish the stock work.
https://www.milsurps.com/images/impo...a031953f-1.jpg

Meant to post this first.
These are the parts after polishing. Lots of elbow grease expended here. The major action parts are case hardened and cannot be draw filed to get the imperfections out like the other parts. There will be more hours spent getting the side cover good enough to blue. You can see marks near the screw hole that will have to be polished out with abrasive cloth.
https://www.milsurps.com/images/impo...d2058a92-1.jpg

Well that's it for the metal finishing. Lots more to do finishing the stock.
Stayed tuned. :)

We'll be watching.

Almost forgot this part.

Lots of good info. Brownells instructions that come with their Nitre bluing salts.

http://www.brownells.com/userdocs/le...g%20Bluing.pdf


Buying Nitre salts.

Brownells sells these of course, but the small bucket is 10lbs. for $66 plus HazMat. For the small amount of parts I need to do, this was a little more than I wanted to pay. By chance, in my quest for knowledge, I learned that this commonly available product is Potassium Nitrate. Springfield's formula also had 10% Manganese Dioxide, but I'm told this is not essential, just a enhancer to the process.

Available at Lowes for $6.44lb. The amount shown in my pot is 2 lb. worth.

https://www.milsurps.com/images/impo...564207lg-1.jpg

That's the hitch here. I'm in Canada and getting that across the border used to be a nightmare, I doubt it's any easier now. Anyone know for sure?

Quote:

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Originally Posted by browningautorifle

That's the hitch here. I'm in Canada and getting that across the border used to be a nightmare, I doubt it's any easier now. Anyone know for sure?

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Can you find "Stump Remover" in your local home improvement store?

I'll see. I know many of the base ingredients are available if you know what to look for.

Just look on the back of the label for the contents. If it says "Potasium Nitrate", you're GTG.
It may not be Spectracide brand, You may find another brand in your area. I read an article where a fellow found this at a nursery in a brand that must be from his local area. He paid $2/lb. for it.
https://www.milsurps.com/images/impo...ng_Salts-1.jpg

The black stuff inside an alkaline battery is manganese dioxide. Just crush it into powder before you used it.

That one I've heard before.

Really enjoyed these two Rust/niter threads. Thank you for posting. What type of pot are you using to melt the salts in? I presume it re-solidified as it cooled. Does the solution become weaker as it is reused?

Quote:

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Originally Posted by Allen Humphrey

Really enjoyed these two Rust/niter threads. Thank you for posting. What type of pot are you using to melt the salts in? I presume it re-solidified as it cooled. Does the solution become weaker as it is reused?

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Thanks!
I would encourage those who want to try these 19th Century bluing techniques to do so. Both processes are low tech and simple to do. All the work is in the metal prep.
The pot used in the Nitre thread is a simple cast iron pot. You can use anything that will withstand the 850* temp. I first tried a bread pan. My only mistake was the one I bought was painted black. I assumed the paint was high temp and would be OK. Wrong. If you are going to use a bread pan, get one that is bare steel.

The salts are granulated when you buy them. After you melt them and they cool down, they solidify, but are easily melted again for subsequent uses. There is no solution to weaken as with parkerizing or hot caustic bluing methods. The salts are simply a medium to heat the parts to the required temperature. The heat itself does the bluing. Small parts like pins and screws can be blued in the flame of a propane torch.

An interesting thread no4 mk1 t, looking forward to the finished article.

Quote:

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Originally Posted by Vincent

The black stuff inside an alkaline battery is manganese dioxide. Just crush it into powder before you used it.

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After crushing several batteries to get the Manganese dioxide out, for parkerizing I decided to buy a container of the stuff from ebay, never give it much thought regarding the stuff itself, but there is a few warnings on the tub, don't inhale and avoid contact with eyes........ breaking up one battery in particular I was covered in the stuff. Whilst ordering the dioxide got myself some Phosphoric acid also.

What is your DIY Parkerizing solution recipe?

Quote:

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Originally Posted by Vincent

What is your DIY Parkerizing solution recipe?

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What parkerizing I've done, I've bought the solution, but here's a recipe I found and intend to try if the chemicals can be found.

Dick Culver is a former Mustang Major in the USMC.




Kitchen Stove Parkerizing

By Dick Culver

NOTE: I originally gave this formula to an interested individual when we were posting on the Ohio site, but it was lost in the transfer. I publish it again here with the disclaimer that I don’t wanna’ be responsible for anyone ruining a $1000 part or becoming a vegetable from inhaling the fumes from some noxious brew. I’ve done it on numerous occasions with no ill effect (some will differ in their opinion of my mental state of course) but if you choose to play around with chemical formulas, you are strictly on your own!

ROC

INSTRUCTIONS FOR "HOME-BREW" PARKERIZING:

You need a number of things to do a "home-brew" "Parker-job", but only 4 ingredients.

1. Phosphoric Acid (the active ingredient in Naval Jelly) usually procured at a chemical supply house.

2. Powdered Manganese Dioxide (a very dense and heavy dark gray to black powder) also available at any chemical supply house.

3. Distilled water (I’ve used tap water, but the distilled stuff gives more consistent results.

4. A biscuit of steel wool (don’t use soap pads or Brillo pads!)

I used to do this on the kitchen stove (I wasn’t married in those days) in a one gallon Pyrex beaker (these little beasts are expensive, so be careful with them). Metal pots don’t work as well (if at all) I understand, but then I never used anything else but Pyrex.



Proceed as follows:

1. Use one whiskey jigger (yeah, this is really scientific, right?) of phosphoric acid added to the water. Remember your high school chemistry, ALWAYS add the acid to the water, and it is best done by pouring it down a glass rod!

2. Use one whiskey jigger of the (powdered) Manganese Dioxide in the solution.

3. Bring the solution to an extremely slooowwww rolling boil .

4. Now add your biscuit of steel wool.

I used wooden sticks placed across the top of the beaker and suspended the parts in the solution using steel or iron "machinist’s wire or some such. DON’T use painted coat hangers or any wire with grease on it! You can usually get this stuff from a machine shop or from Brownell’s.

The parts should be totally immersed in the solution, being careful that anywhere the wire touches the part won’t show on the finished part (usually easy to do – like in the firing pin hole of a bolt). The part(s) to be Parkerized should be totally "de-greased" and sand or bead blasted prior to finishing (depending on the texture you desire on the finished part). Once you have bead blasted the part, you should handle the part with gloves (never greasy hands) and store them wrapped in clean paper towels awaiting the Parker Bath. Any grease on the parts or wire will cause what can only be politely called a variation in color (the parts come out streaked and spotted like a "paint horse").

I usually let the part remain in the solution for a total of 20 minutes (less MAY work, but I was told 20 minutes so that’s what I used and it worked marvelously). When you withdraw the part, immediately rinse it in hot running water to get the solution off of it. Use extremely hot water, and the part will dry itself. Let it dry (and get cool enough to touch) on some clean paper towels, spray on some lubricant and viola’ you are done!

Rumor control said that if you immersed the freshly rinsed and still hot part in Cosmoline, it would give the sometimes sought after "gray-green" tint to it. I have never tried it. Cosmoline is still available from Brownells if you are adventurous!

The original formula called for iron filings vice steel wool, but since I didn’t have any floating around, and didn’t want to file on the cast iron stove, I found that the steel wool worked just fine. What you get is a chemical reaction that causes an iron phosphate to form on the metal (steel phosphate I suppose, using steel wool). I have found that the resultant finish is just as durable as the Arsenal finishes and has exactly the same appearance! – an attractive dark gray, almost black. Some say that adding more manganese dioxide causes a darker finish, but I’ve never tried it, as I was happy with what I got!

We often used this technique when finishing .45s built on early Essex frames that needed a lot of fitting, thus often requiring the removal of offending metal. I used to checker the front straps (also violating the finish in a rather spectacular fashion) and the resultant finish worked great and showed little or no wear even with extensive use – much like the official GI finish. I’m still using a wadcutter gun I performed the magic on back in the ‘70s and it still looks new.

A couple of cautions:

1. Always be careful of any sort of acid, even such an innocuous acid as phosphoric. I certainly would never deliberately inhale the fumes (although there is no great odor to the process that I could tell, but then I smoke cigars). I started doing this back in the early to mid ‘70s and still have no "twitch" that I can directly attribute to Parkerizing on the kitchen stove. Just use common sense, WEAR GLOVES AND EYE PROTECTION ANYTIME YOU ARE PLAYING AROUND WITH BOILING SOLUTIONS (with or without acids being involved).

2. Be very careful not to cause any splashes with the boiling solution (of course the same can be said of boiling corn).

3. Prepare your area and your parts before hand, don’t try to do this on the spur of the moment.

4. Send your wife to see "Gone With the Wind" or "Titanic" or some other movie that whiles away a number of hours. If you ever want to do this again, make sure the kitchen is spiffy when she returns! In Gloria’s case, she would be attaching the parts, but then I’m just lucky in that respect...

5. Once you have allowed the solution to cool, you are DONE! Re-heating it don’t cut it, It simply doesn’t work (I’ve tried it on several occasions). Have everything that you want to Parkerize ready to go when you fire up the solution. You can keep Parkerizing as long as the solution is hot, but allowing it to get cold kills it – you’ve gotta’ brew up a new solution and start from scratch.

6. Do not name me in any divorce proceedings!

Good luck!

Just been reading up on your nitre blue, would this finish turn black if the metal was sand or bead blasted to give a Matt finish. Does the nitre solution spit and bubble like blueing hot salts or does it simmer gently away and how do you deal with evaporation of the solution.
Looking at the formulas for phosphating any one know the formular of the pre dip black parkerizing solution?

Quote:

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Originally Posted by Topfmine

Just been reading up on your nitre blue, would this finish turn black if the metal was sand or bead blasted to give a Matt finish. Does the nitre solution spit and bubble like blueing hot salts or does it simmer gently away and how do you deal with evaporation of the solution.
Looking at the formulas for phosphating any one know the formular of the pre dip black parkerizing solution?

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With a bead blast prep, the resultant finish would likely be a matte blue/black similar to the pics of the Krag parts earlier in this thread, just without the gloss.
The Nitre process involves molten salt as a medium to heat the parts to the temp where the heat turns them blue. There is no solution to evaporate

Potassium nitrate melts at about the same temperature as lead. The amount of time the part is submerged determines the finish. I have used it on parts to bring out a straw color. I usually buy a 5 or 10 pound bag from Duda Diesel. It's used in making bio diesel. They have other useful chemicals as well for cleaning and what-not. I make sure that I get the 99 percent pure as they offer different grades.