doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Oscar's niter blue

Doug check your PM's

We're playing fast and loose with the chemistry here. Substituting different primers in primers in your favorite handload is child's play compared to mixing chemicals when you don't what the expected result is.

"Oscar used laboratory grade Potassium Nitrate and a very small amount of Manganese Dioxide"
This seems correct.

"I wonder where I can scrounge up lab grade PNO3 and some MgO2?"
Well, phosphorus doesn't form nitrates (PNO3 doesn't exist) and what are you going to do with the MAGNESIUM peroxide?

"this thread says Oscar used a "very small amount of Magnesium dioxide"
No, I think it says he used MANGANESE dioxide (peroxide).
Magnesium peroxide is widely used in agricultural, environmental, pharmaceutical and cosmetic industries, but I don't think it's used in metal finishing.

"100 pounds potassium nitrate to 10 pounds of black oxide of manganese"
That would be manganese dioxide (peroxide)

"I use Magnesium dioxie (sic)"
For what? a mild bleach? You can't be using it in niter bluing because it decomposes around 660*F

"I originally used about 10% Manganese Dioxide in my mix but it went bad last year. I don't know what happen, as it started to melt a bunch of black foam kept raising to the surface."
Highly reactive oxidizers can do that. A little contamination and...FIRE!!!

"manganese peroxide is of no special advantage, safe a slight quickening of the process.""
It's a strong oxidizer and rusting is oxidation, so it stands to reason that it would give a little "kick" to the process.

"Also I have no idea what the difference in effect would be between using the Manganese Peroxide Angier mentions & the Mangenese Dioxide Oscar used would be."

None. They are synonymous. The more accurate term is "peroxide" since it denotes the oxidative nature of the chemical, but dioxide is commonly, if somewhat incorrectly, used. In manganese peroxide the 2 oygens are bonded to each other and one is readily released to oxidize other species: Mn-O-O

The term "dioxide" is more accurately applied to a chemical such as carbon dioxide where both oxygens are bonded to the carbon atom: O-C-O
Such an oxide is a considerably more stable and unreactive species than a peroxide.

"I added manganese dioxide per Oscar's formula.....I can't prove it, but the MgO seems to aid oxide growth."
I'm pretty sure you added manganese dioxide and not magnesium oxide (MgO)......but I don't really know.

Do you?

You are right we are being a bit careless here to be sure. Of late, I suspect Potassium Nitrate may be hard to come by in pure form anyway. I suspect I might generate some unwanted attention even in smallish quantities.

Brent

Harry, send me an email at my new address. I didn't receive any PM.

Mike Campbell has certainly done his good deed for the day in clarifying and correcting the mistakes in the recipies presented here. Doug Mann has done likewise in recommending the use of a full face shield, welders gloves, and heavy sweatshirt. This stuff is quite dangerous and capable of putting a careless user in the burn unit, or frying an eyeball and ending your shooting days. When reheating a potassium nitrate pot, the salts can melt on the bottom and erupt through the crust that formed after cooling from the last use. Drilling a few holes with an old 3/8" drill bit into the solidified pot before reheating has prevented this for me. I recall that Brownells Gunsmith Kinks has a tip suggesting leaving a long bolt in the still molten bath as it cools, and then unscrewing it before reheating.

From some source I saved, likely stored here somewhere from a long thread on various metal finishing.

More on Blueing
Date: Nov 21, 19:36
From: Oscar Gaddy
C-man
All true blueing processes for steel create iron oxide films in one way or another. The thinnest are the temper colors or temper blue which gives the azure blue color that you previously mentioned. The films that produce this color are only about one-half weavelength thick for red light or about 30 millionths of an inch thick. The thickness that produces blue black colored niter or charcoal blue (including carbona blue) is about double that, but the increased thickness makes a big difference in durability of the film and the finish. Slightly increased thickness yields the true black colors that can be obtained with both charcoal and niter blueing.

As far as which method is correct for restoration of older doubles, I do not think it makes any difference if the color that was obtained at the factory is reproduced on the refinished part. All processes produce identical films of iron oxide. For example, the original finish on Parker triggerguards was a deep blue-black. This can be obtained by any of the three processes. As you pointed out, it would definitely be wrong to refinish a Parker triggerguard with the dark azure blue temper color or "Nitre Blue" as Brownell calls it.

I believe that Roy Gunther and his colleagues have found in their research that Parker used the niter blue process that produced the deep dark blue-black finish on their triggerguards and skeleton buttplates. I can't help but believe that all of the major American gunmakers used essentially the same processes for the finishing of their guns with some indivudual nuances such as differences in the casehardening colors. The key technical people such as plant superintendents surely communicated a great deal and in some cases moved around from company to company. I believe that , at least before about 1920, all of the gunmakers used niter blueing or a very similar process for small parts such as triggerguards. Old style charcoal blueing is much more difficult to do than niter blueing. They may have switched to the carbona blue process after it became available in about this time frame and it is very probable that Remington used either this process or hot salt blueing for certain parts on the Parkers manufactured in Ilion, NY.
Oscar

Chief
I knew Oscar for roughly 30 years and never knew him to more that a devoted researcher. He was not anti - Brownells but he was very pro doing things right. I may have given him cause to critize Brownells when I pointed out to him other sources for tool room items that were equal or better than Brownells for massive savings. Check MSC sometime. I glad you are getting good results with Brownells stuff but you ARE NOT getting true nitre blueing. Truth does not equal anti, just honesty.
bill

Mike Campbell wrote:



Sorry Sir,...my typo it should have said Manganese not Magnesium







CJ

Ok, I am going to stick my two bits in on this one. These opinions come from restoring a lot of guns, including using heat blue in air, in nitre salts and with my home grown carbonia method developed by trial and error to imitate the old American gas furnace company methods.
And my opinions come from stripping these original finishes off old guns and observing the differences in their resistances to acids and abrasives.
And also listening in on Dan Goodwin and Monte Mandarino discussing period finishes back in the 80's.

Heat bluing I believe was developed to draw parts back after case hardening.
Screws,and hinge pins as they were made of the easiest to machine steel, were hardened as hard as possible, then polished and then drawn back to spring temper by heating to a blue color which with most steels occurs between 650 and 700 f whether you are using flame,or a nitre bath.
The case hardening carburizes the hardened part, so even after is is drawn in the salt bath, it is more resistant to rust then it was before case hardening.
The Salt bath simply provides a way to heat the part evenly,as opposed to a flame or primitive oven and has the advantadge over an oven or lead bath in that you can see the part in the bath, and I think the nitrates were cheaper than lead, back in the day, as they still are.
The salt bath also does not alter the chemical composition of the steel to any real degree, and the blue, whether by flame, or salt bath is very, very thin and can be removed very easily.

Charcoal blue, done in a box with bone charcoal where the part, usually a triggerguard or some other furniture, that has probably not been case hardened because it may warp, and is not as imortant in its hardness being spring temper as a screw or a hinge pin, adds some carbon to the part being colored, and leaves the part in a soft state.
A soft part rusts easier, and this explains why triggergurads and forend latches on old english shotguns are often far more corroded than the parts next to them, including the screws and actions.

Around the time of the civil war the carbonia process was developed leading to the american gas furnace company 's patented rotary furnaces in common use by the major american companies by 1905 or so.
The carbonia blue, which is a creamy black color commonly, is by far the most durable of the traditional finishes. It is applied using an oil to coat the parts, which are heated in the rotary furnace, the rotation acting as a convection oven for even heating and color, and a large amount of carbon transfers from the oil into the steel and makes it very difficult to strip with acid. Winchester appied this so heavily that we have all seen the old winnies with the black flaking off the frame. The black is actually in this case the carburized oil, baked onto the frame.
Colt used the same furnaces and chemical charge to put down a much thinner finish, and lowered the temp to get the fantastic, but durable bluish finish on the early automatic pistols.

All this fabulous knowledge was tossed in the second world war, or shortly after in favor of quicker methods.

There is a good six page article in the August, 2002 issue (Vol XVII, No 8) of the American Gunsmith, "The Official Publication of The American Gunsmithing Association," on nitre blueing. Among other things debated here that are discussed, they mention Brownell's as the source of obtaining the proper equipment AND CHEMICALS. They state the Brownell's salts are a mixture of potassium nitrate, sodium nitrate, and sodium nitrite, continuing with "Brownell's salts aren't quite the same as the original formula (not at all uncommon for a modern chemical formulation) but they do a very good job of duplicating the proper straw and blue colors."

That's certainly my experience, and they have continued to sell this product for many years. It matters not to me (or to the piece of steel I am coloring) that the formulation of the chemical is modern and not "original," the end results are what matters.

I can make a copy of the article available for anyone that really cares about reading it.