Finish, its a black satin

Hot Black Oxide


Q. What is the correct formula of hot caustic bluing for making up a bluing bath for refinishing guns, and can we regenerate the bath again and again, and how can we extend the life of the bath, as I am making the bath in the following manner:
caustic soda 10 kg
sodium nitrate 10 kg
water 10 liters.
The bath forms red cast on the parts which is easily rubbed off but the bath lasts only an hour or so - please advise.

Inderjit Sidhu
firearms - Patiala, Punjab, India +++++

A. Hi Inderjeet,

Forget about your formula search and buy the correct ready-made product from any reputed company in your country.

Khozema Vahanwala
Saify Ind
Bangalore, Karnataka, India - this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hi, I am on the look out for bluing chemicals, details of chemical composition, process, suppliers and pricing details on polished steel parts. The process is hot bluing, on heat treated components.


Rishabh Kapoor
- Delhi, India(2006)

Q. What is the formula for gun bluing hot caustic blueing for home-made. I want to blue my gun. It is old and has rust.

Santi Salinas
- Quito, Ecuador(2007) - this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Does anybody know the formula for the black oxide process? Concentration, chemicals used, procedure? Thanks.

Daniel Hernandez
plating shop owner - Bucaramanga, Colombia (2007)

A. Black oxide formula: 600 gm sodium hydroxide, 25 gm sodium nitrite, boiling solution, immersion 10-30 min, rinse well; it must be oiled, waxed or lacquered.

Use rubber protective gloves, protective clothing and safety goggles !
Hope it helps and good luck!

600 gm NaOH, 25 gm nitrite and 1 lit water!

Goran Budija
- Zagreb, Croatia(2007)

It works. Thank you very much

Daniel Hernandez [returning]
plating shop owner - Bucaramanga, Colombia

Why don't gun shops know hot gun bluing?

Q. Dear sirs:

I have been to many "gun" sites and could not find a formula for "hot" gun blueing. I have found your recipe to be very interesting. Why couldn't I find it elsewhere?

Eric P [last name deleted for privacy by Editor]
- Philadelphia, Pennsylvania

A. Hi, Eric. I'm not sure, but possibly two reasons: first, many of our readers are professionals so they frequently reference and quote the metal finishing textbooks whereas your average gun enthusiast probably wouldn't; second, hot bluing is a dangerous operation that should probably only be practiced in a proper industrial setting, not in a back room of a retail store. Best of luck.

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