Blueing products

Oxpho-blue -- and just follow the Brownell directions

Roger

A friend of mine that gunsmiths uses a recipe of 50/50 (IIRC) sodiu hydroxide (Lye) and ammonium nitrate in a boiling solution. Yields really durable black oxide finish. I think the solution boils at 250 minimum. Steel parts are dunked for 5 - 10 minutes.

Depending on where you're located, obviously it may be edgey trying t get the ammonium nitrate. But, you ought to be able to get a smal quantity without a lot of headache, even these days.

jo

-- Joepy

Sorry about the bad memory. I was way off. Here's a more accurat recipe and process that I found on Google:

Here is the information I promised, taken from "Gunsmithing" by Roy F. Dunlap. (Excellent book, btw.)

5 pounds sodium hydroxide. 2.5 pounds ammonium nitrate. 1 gallon water.

The following is a condensed version of his instructions:

Working temperature is between 285 and 295 degrees F. When you mix the solution, do it outdoors, as a considerable amount of ammonia gas is given off. From 15 to 40 minutes in the bath are required. To us

this solution, the metal parts are degreased either by a commercial detergent like Oakite, a solution of lye, solution or washing with solvent, dried, and placed in the tank. After bluing, they are rinsed in water, either cold or warm, and dried and oiled.

If you have hard water, it is a very good idea to use rainwater or distilled water.

According to Dunlap, this finish is more durable than any other he ha

seen. I have used it for a couple of shotgun receivers and various small parts, and have been very pleased with the results. It seems to wear at least as well as the original finish from Miroku.

Ole-Hj. Kristensen

Jo

-- Joepy

That's "melting", not "boiling". Melting this stuff is bad enough! You don't need the caustic soda, but you have to choose between a higher melting point, or a lower eutectic melting point and a mixture that's now caustic as well as a powerful oxidiser. I can't over-emphasise what a fire hazard this stuff is - splashes onto a wooden workbench are quite capable of starting fires.

Shame to go to all this trouble and just end up with black. This is one of the few blueing processes where it's also easy to get good variegated colour blueing effects.

For "art steelwork", then hot oil blueing is attractive too, but IMHO we've all seen a bit too much of this stuff coming in as cheap import tat for the last few years. I've stopped making it.

If you're doing any blueing, go read some really old gunsmithing books first. This stuff isn't new, but there is quite a bit of skill and experimenation to it.

This is a timely thread. I was checking my older long guns last night and noticed the mediocre bluing job I did on a CVA HAwken kit decades ago now needs re-doing in a proper manner. I deep dark blue or black is preferred. I'm saving all these emails for a free Saturday.

So, where does one buy ammonium nitrate these days?

Rex > >

So what do people heat this stuff up with, and in? I'm looking at a ~20" barrel from a Hawken.

IIRC, for the original job I heated it in an oven, then wiped on the bluing agent (Birchwood Casey something) while it was still 400 degrees or so. Instant blue, but not as deep or as uniform as I wanted.

Black oxide concentrate to make up 1.25 gallon of solution $22.00. or $33.00 for a quart of concentrate that makes up 2.5 gallons of working soup.

Unlike Oxpho blue and others which must be wiped on, you can immerse parts in the Caswell stuff. It does not need to be heated. It makes a nice dense black. It isn't as durable as hot salts processes, but it's very easy to use and it looks nice. I've blackened a number of small parts in a quart of it I mixed up probably

5 years ago. It still works fine.

The penetrating sealer works well, but I think it's just linseed oil and solvent.

Yep Caswells black oxide works fine. I look at the penetrating sealnat they supply more as a linseed/cosmoline mix.....but either way its pretty good.

After sett>>>>

Iron kettles. Avoid stainless, wrought or cast iron are better. If you weld one up from mild steel it will work fine, just not last so long.

Heating should be electric and thermostatic, for easy control. Get some firebricks and set cheap oven elements into grooves in the top. You don't even need to grout with fire cement (expansion tends to blow it out anyway) and you certainly don't need bare-wire elements. The only expensive part is a good controller - any industrial electrical supplier will have these and they're still cheaper than most kiln specialists. A kitchen "simmerstat" or triac phase controller is almost enough, but you have to guard manually against overheating - these just control power, not temperature. Accurate thermocouple meters are dirt cheap these days

- crazy not to have one.

Nitrates are available from lab chemical suppliers. They _will_ still deal with you, if you're patient. Failing that you can use fertilisers or refine horse urine (crystallised leachate from a big pile of used bedding straw is simpler to work with than draught). The purity you need is trivial in comparison to pyro uses.

An awful lot of successful hot bluing gets done on the kitchen stove in a stainless fish kettle. It works OK, but I wouldn't recommend it - this stuff is just too hazardous. Personally I only work on stuff this crazy if I'm outdoors and "firefighting" can just be a question of leaving it to burn itself out.

Sounds like a lot of effort for a single barrel. Thanks for the detailed response.

Well the kettle can come from a kitchen shop, or just 5 minutes with the welder if you need an extra long one. A portable electric hotplate is a good thing for any workshop.

The business with the horse piss is because everyone who shoots black powder secretly hankers after producing their own saltpetre and then gunpowder, just to piss off the regulators 8-)

If you don't have a horse, you can plumb the outhouse like they did in the South during the War of Northern Aggression.

I'm from Lancashire. Those Yorkshire types over the hill used to collect barrels of it. Supposedly it was for washing woolen fleeces down in the sheepmines, but I've been to Tadcaster and I know the real secret.

Human urine is of little use though - you want horses, because you want big high-volume herbivores and cows have a relatively wetter diet, so it's more dilute.

No personal experience. I just recall a civil-war era photo in one of the Foxfire books, in the article about rifle-making.