I came across this in an old book in my local library. It is said to produce that thick, nearly black finish found on early K-98's:

Ingredients

1. 5 lbs Lye (sodium hydroxide,Drano)
2. 2.5 lbs ammonium nitrate
3. 1 gallon distilled water

Directions

Mix ingredients in black iron container and bring to a boil between 285 - 295 degrees F. Emerse metal in boiling solution for 15 - 40 minutes. Remove and boil for 5 minutes in plain distilled water. Dry and oil.

Comments

Author claims blueing is "extremely durable".

Bobster,
What was the name of the book? I'd be interested in hearing from anyone who has used it recently.

Eric

Mauser416:

Can't remember name of book, but will look next week. I will post when I find it with attention to your screen name.

Bobster

Bobster---

That's the rough formula for all "hot dip" blueing. It's not nearly as tough as rust blue but much cheaper and easier to do.

You'd be much better off buying a box of Oxinate #7, DoLite, BluBlak, or other commercially available substance. It's the same stuff.

Got to www.abe.com and buy the book, "Firearm Blueing and Blacking", by R. H. Angier.

I bought an original 1st edition, printed December 1936 for $25.00. This has about 230 recipes and most with instructions and comments.

I agree with JBelk. You'll get a uniform, dependable product that way. Boiling point is controlled by the water content of the blueing salts, by the way, not the heat input.

Bobster

The bluing formula you mentioned came from "Gunsmithing" by Roy Dunlap. To quote Mr. Dunlap "In appearance and wear resistance it greatly resembles the finish used by Germany on military small arms prior to 1942. The black produced by this amonium-nitrate-lye process is unbelievably durable. A finished part will take a wire brush test without damage which would totally remove almost all other finishes".

I have that page ear marked in my book as I always intended to test it but never got around to it.

Bobster, Craftsman et all. in re Caustic bluing process using Assault Fertiliser and the lye the meth cookers like to use. Yes, you read that right. Getting the chemicals could be a problem. I have used that formula since late 1945. By 1980 because of the OSHA regulations Suppliers legal counsel made it tough to get 96% + purity lye (sodium Hydroxide in FLAKE form). Anything less in purity or below 90% and you start having trouble calculating how much extra to add to get the proper equalibrium between the chemicals. A lye in the form of pellets ("prills") is worthless because it has a coating which acts to retard and nearly stop the process + you cannot isolate it out chemically. If you buy it in lots of about 800 pounds the supplier usually decides you arent a meth cooker and are probably legitamate. The 96% + grade usually ran about 38 cents per pound that way F.O.B. loading dock. the ammonium Nitrate should be about 98% pure or more. Currently because of Tim McVeigh and the first World Trade Center bombing there is a contaminated grade the dealer at the feed store will try to push off on you. You will litterally have to shove your F.F.L under their nose to pry the usuable stuff out of the dealer. Craftsman may be able to get the lye easier. The grade used to clean stripper oil well casings is acceptable.
The lye sold in specialty food stores for making your own pretzels is Food grade and cheaper than Draino as is the food grade used to peel carrots and potatoes.(than draino)
Is this solution better? Absolutely. The result is a chemically pure sodium Nitrate which in that grade is DAMNED expensive. When you mix the stuff you want to be up wind even if you need your sinuses cleared. There is a great liberation of Ammonia gas until the mix achieves equalibrium. The maximum ammount to mix should not exceed 9 pounds in the at least 2 gallon steel pail. I said STEEL not galvanized steel. ( Lye eats zinc with great gusto and the gas from that is bad on you) The mix generates a great deal of heat. You start with the lye- 2# by weight in the pail and add a half liter of water slowly then stir with a wooden stick until the reaction subsides . Then you sprinkle the pellets of Nitrate, back away then add more until you have used the pound. Slowly stir in the remaining water. It will be like a thick soup. Now slowly add the next 2 pounds of lye . Same drill for the remainder until 9 pounds of chemicals are in the pail. Stir it a while to make certain the nitrate is thoroughly united with the lye. 1 Liter of water for each 3 pounds. When you finally have your vat filled to within about an inch of the top edge you can turn on the burner. From about 245 deg. to 265 the solution will liberate Ammonia but no stronger than in some of the household chores. If uou have a part wired up it will probably blue almost instantly first time out at that temp.( 265,when the gassing stops) This solution does not leave the bite in the air, and will blue(black) steels that are a real hassle with the store bought stuff. The Nitrate only leaves solution from drag out. The lye converts to sodium carbonate from carbon dioxide in the air and this is the stuff that collects on the sides of the vat and settles to the bottom, and should be scraped out using a flat blade bottom scraping tool (looks like a solid spatula with a long handle) By apparent volume whatever you toss out -you replace with lye. I never threw out my solutions until I moved locations It doesn't wear out but the lye needs to be constantly replaced. Best procedure is to put the parts in from about 275 Deg and not over 285 (F) then let the solution get up to around 300 deg F. Forget the stop watch. Some low carbon stuff needs more time and about an hour cycle catches virtually all. Is it worth the trouble? Yes, with out qualifiers.
If this scares you and it ought to since in order to protect yourself from very serious chemical burns you need to suit up for the project, Face mask, rubber gloves long sleeved shirt, Water hose to flush yourself with if the stuff spits at you - this is serious chemistry, Trousers to the shoe or boot tops etc. Remember. Lye eats concrete, Grass, and just loves leather as in shoes or boots. Ammonia Quits after first heat up.

With all of the above has anyone tried that Industrial blackening stuff that goes on at 190 degrees doesn't use Hot caustics can go down the city drain system and is sold by Casey Chem in Minn., Another out fit in Wiasc. and a 3d in Kalif? ( and is supposed to be "More durable than that awful stuff your plant is now using" )

Thos. M. Burgess

Thanks for some very good information. Thats very astute of you being aware of the oil field economy around here, what little is left of it.

I have been reluctant to persue buying bulk quanities of amonium nitrate and sodium hydroxide around these parts due to the methamphetamine labs you mentioned. It's really an epidemic in this area and I just dont want to get funny looks and pointed questions from the dealers.

Last year I bought a 500 lb drum of Black Magic bluing salts from a supplier in Oklahoma, hauled it myself and ended up paying about half of what Oxynate 7 was costing me. I cant use those kind of quanities my self, I will decant some of it into 40 lb pails and sell it to my gunsmithing friends.

Having said all that, do you feel using the formua we have been discussing has any advantages in durability and appearance over the commercial type? I was told by the supplier for Black Magic that some of the other commercial bluing salts had a lot of additives in them that made them more difficult to use and degraded the durability.

Craftsman, I wouldnt be too worried about buying the bulk chemicals for the following reasons; meth cooks use the anhydrous type of ammonia, the liquid type is used in the generator to powder the final product out. As to the lye, most cooks buy the small 32 oz. bottles at plumbing supply houses, I have never seen anything larger than that on any seizure that I have been involved in. And if you read the local papers you know that has been several lately. I have been away from this BB for several months and this is my opportunity to get my feet wet again. Just my two cents,
Eterry

Good Luck and Good Shooting

E Terry & Craftsman

My remarks were based on my own experience but moreso that of others who got the formula and directions for use from me, sometimes in the long ago past. The high purity grade of ammonium nitrate IS used for explosives, and for legal worries the dealers are fearful of selling the stuff to persons not known to them. When you tell them it is going into a gun bluing solution they start rolling their eyes and you end up talking to the manager or the head office. It never got to that point with me because It is evident that I'm not going to back down and can write out the formula in Chemistry book fashion. This did happen with one bluer and he was armed with the formula and soon lost his questioner in fine chemical jargon- which was all that the seller needed for assurances. He also had a copy of his F.F.L. As to the lye ... Large quantities and the sellers worry about some process going awry and then THEY will get roped into a law suit and harrassment by both E.P.A. and O.S.H.A. for being a facilitator that ought to have known better. Grocery store or plumbing shop quantities and most clerks and store management have been briefed by D.E.A on what to look for and how to report any suspicions that they may have about potential buyers of the material. (in this area)

The solution we are discussing will without much trying give a better and more durable finish than you can get with fresh, first time use solutions available to the trade with the same ammount of indifference. The reason is exactly in what your Okla. supplier told you. Additives to make up for less than top grade raw chemicals. The best results with any of the lye/nitrate combinations will not go any deeper in low cabon steel than about .0005" on a decent polish job,and on hardened carbon steel such as was used on ring and snap gages- metalworking industry- the depth was .0002. The only measuring method they had was lapping the surface with a diamond impregnated lap and then under the microscope until the last island of "converted surface" had disappeared. This was the result of an experiment at Packard Motor Corp during WW II in the plant where they made Rolls-Royce aircraft engines. They determined that there was more wear and tear on the engines "in the field" from over maintenance. Someone with firearms experience wondered about bluing the usual suspect parts to see if when the blue wore off that might indicate something. It did and they developed access windows in parts of the engine. No blue left at point xyz meant time for tear down. Then they had to know how much wear that ammounted to (for proof to the U.K. Purchasing commission) Further result, they blued all their manufacturing gages. Can't see any blue on the contact surface = time to replace. The chemical combination they used with very little change became "BLU- BLAK". it was very little different upon analysis than what we are discussing. Surface preparation is still the key to a durable blue. My conterfeit rust blue was simply 150 grit garnet sand blast followed by careful wirebrushing using a wheel made of carbon steel wire .0035 to .004" dia- & wheel dia usually 6" and run at about3400 RPM. This under microscope gave a surface of peaks and pores. Pores hold oil. Peaks are so small that when they do wear the blue doesnt appear worn - except under the microscope. What happens with the stuff containing the additives? The goody goody goes leaving a bunch of temporising additives. Instructions will tell you then to throw that out and start fresh. C.C.P. Sodium Nitrate cost $3.55 per pound 50 years ago. 40 pound sack of Ammonium Nitrate cost $ 3.87 same time. Go Figure old miserly never-sweat here. If you haven't cleaned that pea- soup looking stuff that starts to settle out when the vat has cooled to about 250 deg. it will boil with the solution next session. Put a part in at too high a temp and the stuff plates all over the part. Miserable to remove even chemically. The solutions with additives tend to be much less forgiving on that score plus there is frequently some of that residue on the part with the blue. If it is thin enough the oil will disolve it leaving a less thoroughly blued surface. It seems like the immersion process bluing has a 2 week plus cure to go through to complete some sort of arcane chemical or physical link up. Not unlike gunstock finishes I suppose.

A rule ought to be, " If you get excellent results with what you are using now and you are NOT uptight everytime you crank up the tanks through the session DON'T change"!
There isn't much up tight with the Amm Nit/Sodium Hydroxide mix. I'd have gone to Krylon Mid nite blue in the Spray Can had it been so. It's hot enough in the summer and I don't need extra sweat.