Blue 1

[Linstrum]

Our local library had their copy of Dunlap's book stolen just recently.

I need Dunlap's recipe for hot bluing and blacking, it is a good one and is simple. It uses Grant's stump remover and Drano "kitchen crystals" as the two ingredients for one version, the other uses ammonium fertilizer and Drano. The key ingredients are actually potassium nitrate and soda lye.

I made up some solution from memory and I'll be darned if I can get it to work! Usually to test it you drop in some nails and let it simmer for a fifteen minutes and you have the blackest, shiniest nails you ever did see. It is also a hard scratch-resistant bluing-blacking treatment, it withstands hard use just great. The down side is that it is not blue - it is as black as black can be. But it is EASY, - - - IF the recipe is handy! I do have a hunch that the stuff Drano sells nowadays is not lye because of the problem with droogies using it to make crack or some such mind-altering substance, and that is why my bluing solution no longer works.


rl316

[danski26]

I have Roy's book in hand. On page 391 he lists "Bakers basic solution" for hot blueing;

sodium nitrate 1/4 oz
potassium nitrate 1/4 oz
bichloride of mercury 1/2 oz
potassium chlorate 1/2 oz
distilled water 10 oz
spirits of nitre 1/2 oz

Is this the one you need?

[Firebird]

I think Linstrum is referring to the formula on page 399 of my NRA published copy.

5 pounds lye
2 1/2 pounds ammonium nitrate
per gallon of water

working temperature 285-295 degrees, soak 15-40 minutes depending on the hardness of the steel.
Have lots of ventilation when adding the ammonium nitrate as considerable ammonia fumes result.

Dunlap attributes this formula to Don Lowery and says this produces an unbelievably durable finish that can take a wire brush test without damage.

[Linstrum]

Okay, thanks, guys. Got it.


I had no idea that there were several different versions of the book, some with the recipe I wanted and some without.

For twenty years I modified the easiest formula of the bunch to make a REALLY durable hot black solution. I was using the formula on page 398 modified as follows:


65% Lye (aka sodium hydroxide)
35% Potassium nitrate (aka saltpeter)

Don't use the Drano lye crystals with little chunks of aluminum in it, the aluminum will prevent the solution from working. Use eye protection since a little lye in the eye may cause severe damage, even blindness. Mix the dry ingredients and than add enough water to make into a damp paste before heating. When heated it will turn into soupy liquid. Simmer your steel parts in this until the black surface is formed; probably in about 20 - 40 minutes. Like it mentions in the book you can't take the blacking off with a wire brush - plenty hard stuff!


rl417

[drinks]

Most auto parts stores and hardware stores have the phosphoric acid, brand names are Ospho and Rust Stop, here locally.
For cheap potassium nitrate, check the sites for making amateur fireworks for technical grade, non food grade, material.

[XRING363]

FYI, stump killer is a very good source of potassium nitrate, 99% pure, 4/5 dollars a pound at Lowes/Homedepot.......

[Catshooter]

Gentlemen,

IMPORTATNT SAFETY TIP; You do not plug the barrel when hot blueing/blacking. As the air you've trapped in the barrel heats up the match the 290 degree lye solution it will expand alot and the odds are excellent it will blow out a plug. That can propell lye solution into places you didn't plan for it to go!

That blueing solution is dangerous stuff. Please make sure you understand what you are doing before doing it.

One does want to plug the barrel when Parkerizing. The solution is corrosive and at a much lower temp. The blueing solution can/is corrosive, but it's much slower, takes days.

"Add water . . ." Such a simple statment. Adding water to a working blueing bath is a bit like adding water to the working lead pot. Neither the bath nor the water like it! That hot lye on skin doesn't quite burn like liquid lead but it ani't pleasant by any means. And in the eye? Oh no thank you. Please don't wear safety glasses, wear goggles at least.

Sounds overkill, but a construction hard hat with the type of safety face mask that attaches to it is good. Can help from getting the solution behind your ear or down the back of your collar. Of course the long sleeve cotton shirt you're wearing is buttoned all the way to the neck, right?

Sorry to be so long, but there are just a few tricks to this work. It's like cooking bacon naked; not a good plan.


Cat

[sundog]

Junior, +1. I've done a couple with flat black exhaust manifold spray paint. The high temp stuff. Not sorry I did. Very durable. Good looking.

[Molly]

Here's a write-up on Caustic Blue that I did years ago for a neighborhood kid that was interested.

Molly
"Gun Blueing"
(Caustic Black Iron Oxide)

Bath Formula

Ingredient Chemical Weight Weight
Materials Symbol Measure Ratio One Gallon
Water (softened) H20 4 Pounds 64 5.2 Pounds
Sodium Hydroxide NaOH 4 Pounds 64 5.2 Pounds
Sodium Nitrate NaNO3 1 Pound 16 1.3 Pounds
Sodium Nitrite NaNO2 1 Ounce 1 1.3 Ounces

Some Primary Hazards
(A partial listing)

These chemicals can be dangerous. NaOH ("Caustic") will rapidly attack flesh, clothing and many metals. Spills should be flushed quickly with vinegar to neutralize the caustic and minimize damage. Mix dry caustic into the water in 4 or 5 small steps to avoid boiling the solution, or use commercial 50% caustic solution. Wear caustic resistant gloves, aprons and eye protection at all times. Don’t use bore plugs, which will splatter hot caustic if they pop out. Dry NaNO2 and NaNO3 can be explosive, just like lawn fertilizer.

Bath Operation

The solution tanks must be un-galvanized iron, steel or stainless steel, with welded seams. Soldered or brazed seams will dissolve, ruining solution, tanks, and whatever gets leaked on. Adjust the bath to boil at 275 F (135 C) to 302 F (150 C) by adding water slowly through a large fine steel mesh to catch spattering caustic. Don’t go over 310 F (155 C), or the solution will be damaged. Turning the heat down won’t work, as the bath must boil gently in order to work properly. Handle parts with steel wire hooks or tongs. Degrease before bluing in a hot detergent or caustic solution and rinse well. Then put them in the hot bath right away. Hang them away from the sides or bottom of the tank, but small parts can be placed in a steel wire basket. Let them boil for ~ 10 minutes, then remove and rinse in clean cold running water. Check color after scrubbing with clean, degreased “0000" steel wool. Return to the bath until the color is good. Rinse thoroughly, dry, oil and reassemble.

Trouble Shooting

Polish your metal well. Blueing won’t cover poor polishing. Poorly polished white steel becomes poorly polished black steel. Protect polished parts from rust with light oil until ready to degrease and blue them. Anything a magnet won't pull on (like wood, glass, aluminum, plastic or stainless steel) won’t blue, so don't put it in the bath. It could dissolve and ruin both the part and the bath. If a used bath is heated but won’t work, try adding a little more caustic or nitrate.

No color, or red or purple tones can be due to low temperature, copper contamination, low NaNO3, high carbon alloys or too little time in the bath. Green or pale blue colors can be caused by low temperature or not enough boiling action in the bath. Splotchy or un-colored spots can be caused by poor cleaning or oil contamination. Sometimes this can be fixed while blueing by scrubbing with degreased “0000" steel wool. A powdery black that scrubs off is caused by a worn out bath. No color can be caused by a worn-out or overheated bath, wrong amounts of chemicals or (in old baths) by caustic being used up by CO2 in the air.

[Molly]

BTW fellows,
I've noted ammonium nitrate recommended in some of the above formulas. Believe me, you'd better have an outdoors operation if you try it. I speak from experience! You'll be a lot beter off to substitute sodium nitrate. Still works, no ammonia odor.

[Newtire]

Hi all,

Sounds like something I'd like to try-this bluing thing. I have a couple of questions though.

1. How do you keep the inside of the bore from rusting if you can't use a bore plug..

2. I see that some of the postings list common sources of chemicals, others don't.

Is there a source of these chemicals and where can I find out how to obtain them?

[Junior1942]

>Sounds like something I'd like to try

Sounds like something I'd avoid like the plague.

[Molly]

Hi all,
Sounds like something I'd like to try-this bluing thing. I have a couple of questions though.
1. How do you keep the inside of the bore from rusting if you can't use a bore plug..
2. I see that some of the postings list common sources of chemicals, others don't.
Is there a source of these chemicals and where can I find out how to obtain them?

Read Post # 9 above. Blueing isn't something to be undertaken on a whim. It's hot, dangerous work, requiring STRICT observation of safety rules and procedures. There is a substantial potential for serious injury if you are careless. If your personality is such that you don't want to be restricted, find another hobby. If you can and will follow directions, have at it.

As to sources for these materials, they aren't hard to find: Sodium Hydroxide is ordinary lye or caustic. You can buy it already dissolved as an industrial commodity 50% solution, or as dry white pellets. I've bought it at the grocery store, but that was an emergency. Most chemical companies keep it on hand by the tankwagon for cleaning. If you go the pellets route, read the procedure for dissolving them and follow the instructions carefully!

Sodium Nitrate is an ordinary farm fertilizer, obtainable at feed & seed stores nationwide.

This is all that's REALLY necessary, but sodium nitrite is a good buffer, and gives a better quality and depth of finish. I buy mine from a chemical supply house, but I'm sure there are other sources. Get technical grade material.

[Newtire]

Thanks for the info. I hear you about it being dangerous. Not just a whim here, been wondering how to do this for quite awhile. Would be worth a try I think. Don't worry, I'll be careful I promise!