Letter 0019

Blackening Stainless Steel

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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 H [last name deleted for privacy due to age of posting]
UC Santa Barbara

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
Operating temperature, 210 degrees F.

 

Proprietary processes are available from such suppliers as:

Electrochemical Products Inc. (EPI) [New Berlin, WI] and

Heatbath [Springfield, MA]

There are also stainless steel anodizing processes offered by B&M Finishers [Kenilworth, NJ] and a stainless steel black passivation process offered by Russamer Labs [Pittsburgh, PA]

Ted Mooney, P.E.  finishing.com Brick, NJ

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

Ed. note: You are correct, Leslie. People will get the best answers to their questions if they remember the reporters' credo of who, what, when, where, and why :-)

I want to post a question or inquiry of my own.

 

I want to answer this question publicly

 

This letter is within a monitored forum, very much "alive" here in 2008. If you spot any broken links or obsolete info, please advise!