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How to Blacken Stainless Steel

Adv.   

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Q. Hello, I'm looking for information on the processes available for blackening stainless steel. If you could direct me to any publications or services, I would greatly appreciate it. Thanks,

Terry Hdeleted
UC Santa Barbara, California
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A. Hi Terry. The Metal Finishing Guidebook lists 3 formulations of blackening baths for stainless steel. The one that sounds simplest to me, although I can't comment on its efficacy, reads:
- Sulfuric acid, 180 parts
- Water, 200 parts
- Potassium dichromate, 50 parts (Potassium Dichromateamazoninfo)
- Operating temperature, 210 °F.

Proprietary processes are also available. Although we don't discuss or suggest particular brands in the forum, the forum is supported by advertisers who offer proprietary blackening products =>

There are also stainless steel anodizing processes and stainless steel black passivation processes. Good luck.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

Adv.

EPI blackening processes for stainless

Heatbath blackening processes for stainess

Stainless steel anodizing: B&M Finishers

Black passivation of stainless steel: Russamer Labs


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A. Terry,

Your question did not specify what purpose the blackened stainless steel is to be used for.

Some of the components inside a TV tube must be "blackened" using a process of heating and cooling in a controlled atmosphere.

Leslie R Williams
- England

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Ed. note: Please listen to Leslie, folks. People get the fastest and most rewarding answers to their questions if they employ the reporters' creed of "who, what, when, where, & why" when posting their question :-)


September 14, 2011

A. If you heat stainless with an oxy-acetylene torch (neutral flame) until it has an orange glow uniformly, then let it cool naturally it will remain black. Polishing with steel wool and metal polish enhances the finish. This is for cosmetics only. It is a very hard finish but will scratch with sharp objects. It is black about .002" into the metal.
Repeat the process again with a warm water quench and some stainless will harden. The blackening occurs because the chrome and nickel are being burned out. The remaining metal seems to be the same strength, toughness, etc.

L.A. Jones
- la mesa, California, USA


October 17, 2012appended

Q. Is there a simple way to make chrome steel rods black in color?

Worth Hayden
- Winnipeg, Manitoba, Canada

October 20, 2012

A. Oil it very sparingly, and then heat it to 200 - 400 °C (slowly). Any edible oil or fat can be used, but linseed is the best. You can use hot air gun as source of heat. Hope it helps and good luck!

Goran Budija
- zagreb, Croatia




Q. I have started to produce jewelry (Rings) using stainless steel and want to blacken the surface. Any suggestions would be gratefully received. I would prefer a dark, matte finish.

Thanks,

Burt Qwallis
- UK


 

adv.
Burt, please visit our web site - there is a picture of the black finished stainless steel spoons. Quality of the picture is not perfect: the spoon from the right is matte black, the very left one is bright dark blue. In the middle is bright black.

anna_berkovich
Anna Berkovich
Russamer Labs
 
Pittsburgh, Pennsylvania


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Q. How do you prep stainless steel to accept oxidizers that will color it black in the field for example elevator interiors or doorways and entrances at high-rise office buildings.
#2: What type of chemical will work if not oxidizer?

Harry Smith
- Brisbane, California, USA



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RFQ: I am looking to have my Smith & Wesson Stainless Steel Revolver blacked. I had the process done to another of my SS revolvers over 12 years ago. Their site mentioned that it produced it's "black coatings on stainless steel and alloy steels by a "conversion" process. The chrome in the stainless steel is involved in a chemical reaction with the oxidizers in the solution producing chrome-sulphide." The finish has held up exceptionally well but that shop no longer offers blackening of Stainless Steel. Please email me with any information.

Thank You,

Adolph Alvarez
Hobbyist - Vista, California, USA
outdated



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Q. I need help blackening or darkening Stainless Steel,

Parts are approx. 20'x 6" x 4"

These pieces need to be welded on site.

Should parts be treated before or after installation?

Will welding affect pre-treated parts?

What Process can be used to do this?

Grateful for any help!

Marisa Ldeleted
Casting Foundry - Beacon, New York
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