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Coloring and Blackening of Stainless Steel




Q. Hello. Greetings from Argentina !
I'm Industrial Engineer, and I work with Stainless steel for a body jewels company.
I found a chemical solution for blackening steel (316L and 304). Yesterday, I test it. It's Good! But I lost the shiny surface.
Basically, the solution is Molten Sodium Dichromate. Immersion of the piece about 5 minutes at 300 C.
I need to know if this method can change the biocompatibility of the steel. And if is possible obtain a bright surface, like before the immersion?
If it is possible to, the method for coloring the steel. Thank you very much.

Ezequiel Rosler
Industrial Engineer - Capital Federal - Argentina
2007


A. Sodium dichromate is carcinogenic compound and I think you can't use it on jewelry items. You can silver or copper plate stainless steel; after that you can treat it with potassium polysulfide solution. Or you can use old burnt oil process -- oil it very slightly with linseed or any other edible oil (or 20% shellac solution), then heat it slowly to max. 400 °C (with hot air gun). Hope it helps and good luck!

Goran Budija
- Cerovski vrh Croatia


sidebar Wake up US manufacturing - this used to be a predominantly US dominated website - both questions and answers. Now we've got Argentina posting questions and Croatia responding. Anyway . . .

A. There are alkaline black oxide processes specific for 300-series stainless that don't significantly dull down the surface. They basically convert iron to the black form of iron oxide (as opposed to the red form, i.e., rust as we all know it). I can't see how that would change anything in the "biotoxicity" of the parent stainless steel provided that it's rinsed well.

milt stevenson jr.
Milt Stevenson, Jr.
Syracuse, New York


sidebar

opinion! Yes the site used to be USA-dominated, Milt, but of course reflects the world situation.

None of the "big three" plating process suppliers is American anymore, and most of the 2nd-tier process suppliers market to and manufacture in China. Most large USA equipment installations are by Europeans these days. Attendance at AESF meetings is discouraging. I know three good-size NJ plating shops that closed this year. The "arsenal of democracy" is empty with no manufacturing capacity left to refill it, and nobody is appropriately scared. Like you, I do what I can, including keeping this site going, but the American public doesn't know or care about the straits we are in. (Well, this thread earned a big red "opinion!" sticker).

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey


thumbs down sign Well, its sad to hear that the so-called experts in this website or the guys running this site feel that this website was created for US people. In the first place the website is "www" means world wide web, from the word itself world wide, so it means it people from all over the world with metal problems come here for a consult or try to have an opinion on what's going on with their metal stuff. You might as well change the name US.finishing.com, so that it would be exclusive for white Americans with big ego's know everything "expert in everything".

It's cool to be recognized as experts. But it's annoying for these experts to feel that they are above anybody else.

Barry M. Umacob
- Cebu, Philippines


thumbs up sign We're delighted to print your opinion, Barry, but the only person who has insulted anyone is you. Yes, I grieve that many of my friends lost their life's work recently and had to discharge their employees due to my country's inattention to the direction we're headed, and I won't apologize for grieving :-(

But you should apologize for your remarks :-)

BTW, the three New Jersey shops that I mentioned closing this year were also all advertisers who had been helping make this site possible for the world to benefit from; you apparently feel entitled to have such forums, but they can't exist unless someone pays the costs and I don't see your company supporting this forum :-)

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey


opinion! I know almost nothing about coloring of SS, Mr. Umacob, and that's why I didn't comment, but I know about generosity and democracy. You're right on the www concept, but the rest of your opinion seems out of context, emotional and unfair. Milt was trying to encourage his US colleagues, not to exclude or devalue people from other countries. He also gave an expert opinion to the inquirer. That's generosity. Ted shared a well informed view and critique of the situation in his own country without offending others. He also swallowed his pride and posted your letter. That's democracy. My vote goes for them, and that's a red sticker too!

Guillermo Marrufo
Monterrey, NL, Mexico


As you said, this site was set up initially and intentionally in USA, now it goes world wide, Does not it mean you are very successful? Is not that why you get so many advertisers (sponsors)? Be chemical suppliers, instrument manufactures...

You are painful to see some plating shops close down, you will be (me too) more painful to see this site shut down.

We understand your feeling for this, but you need to understand also that it is just like two sides of one coin, at one side, plating houses closed for the so-called globalization, but at the same time on the other side, chemical suppliers and instrument manufactures in USA make lots of money from the so-called globalization too.

John Hu
- Singapore


thumbs up sign Thanks, John! I said the site was dominated by USA visitors years ago; I didn't say it was set up for the USA, and it wasn't. Rather, it's been online since before the internet existed, back when people had to pay for the phone call; so, due to the high cost of international long distance calls, nearly all visits were from the USA in the early days.

My visit to Singapore some years ago remains one of my fondest memories and I wish you and your countrymen all the best. The fact that I am pained by the current anti small business attitude of my own government and our own people doesn't mean I bear ill will towards people in other countries. I've learned a great deal both technically and about life from the postings here and I feel HONORED when people like Ezequiel, Goran, Barry, Guillermo and you choose to use this site.

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey


I think the Webmaster is very much right on. Our work has gone overseas, and I celebrate our foreign counterpart's success. The Lord of Commerce has smiled on them, and it is their day.

We have accomplished exactly what we set out to do - make every job in the USA one involving long hours in front of a computer in a clean, climate-controlled environment. Yes the US is losing its "Warm Base" in manufacturing. On my "Day" job, (the one that pays the bills), I work in the Defense industry. It is almost impossible to get anything actually "Made" in the US these days. One reason is a lack of skilled workers. It is next to impossible to persuade anyone entering the workforce to enter the manufacturing trades. I was a tool & Die Maker for 15 years. I had to switch careers because the jobs dried up here and I was reluctant to move. Many who did move were out of work in six months.

No, the problem is very much our own making. We have eliminated vocational training in our educational system. I graduated High School in 1969 (Yep; I'm an old Far_.) and even then, if you wanted to go into the skilled trades instead of going off to college, you were treated about the same if you suddenly publicly announced you were going to go into the "Adult Film Industry" at Career Day! You were treated as beyond hope. A loser - No College. No Future. (No girls, either - who wants to get in a relationship with a LOSER that gets DIRTY!)

Well, in the years since, I did get to college, but I also spent 2 years in vocational training that was as challenging as any college course I ever attended. But, I believe I was among the last young men (and women) that wanted to actually "cut metal". We CANNOT set up a simple manufacturing facility in the USA any more. We have lost the expertise and the knowledge of how to make manufacturing work. We used to insist that 95% of a defense-related part be manufactured in the USA. That was not Chauvinism or Jingoism, it was NECESSITY! If the commerce lanes suddenly get shut down by an enemy, you had better have resources and knowledge to be self-sufficient as you are not going to be able to import anything for the foreseeable future. We have lost this warm base of manufacturing ability, and by removing a generation educated in these skills, we have dismantled the ability to regain it. All the old tool & Die men are deceased. Even those that became CAD specialists are mostly gone. And, we cannot even train anyone "how" as we dismantled the educational system that was responsible for their creation. Besides, you can make more money trading futures!

Since then,I have seen the Engineering field deteriorate significantly. Now, what I am about to relate is not a sexist diatribe. I have worked with several female P.E.s' I regard as at the top of their field. I have toured plants, been in conferences, and been very impressed with their expertise and professionalism. And I have seen many young men with a P.E. to whom you had to explain the function of a screwdriver as they didn't own one. And had never held one, and were not going to break that perfect record! But, the worst manifestation of this trend was on my "Day" job -(The one that pays the bills, not my gun shop; fun, but not much $$$). I had to call a recess to a Engineering Change meeting while I tried in private, to explain to the young Lady P.E., 25 years old with a Master's and a PE, and was the Head Engineer on a major government procurement contract for an avionics frame used on a ballistic missile. This part had to have a 20 year (between inspections) shelf life as a spare part. The contractor wanted to (1.) change the aluminium T6 alloy to another alloy (I can't recall what), and (2.) change the welding process at the same time. I argued both processes (and the anodizing process as well) needed to be re-proved. The contractor showed my engineering colleague a statistical model that "proved" without a doubt, there was "no need" to re-qualify either process. Well, since my colleague had a Math degree this was Proof Positive the Process could be Controlled, and my objections were dismissed rather quickly. In a later memo to my Boss, she objected that someone without a PE would be allowed to attend a meeting like that, my "obstructive behavior" (?) had "wasted time". I never could make her understand why the process needed re-proving of the inspection process. She kept repeating "aluminium is aluminium". Thank goodness the contract was later cancelled, she went to greener pastures, and no parts were ever made this way.

We are buying much of our defense items off-shore now, from M-16 magazines to sophisticated electronic apparatus used in fighter planes, tanks, and shipboard electronics. Generally, this is done by "outsourcing" through the US contractor's overseas plants. By careful wording of the contracts, this can be legal. But, think what you will about the Defense Industry, one fact remains: It always was a good training ground for manufacturing jobs. I know - Been there, Done and Seen That. Yep, "we have met the Enemy, and It Is US!" My congratulations to our overseas friends. You have showed intelligence, resourcefulness, and initiative, and I always admire a skillful player in any game, who works hard and recognizes weaknesses in their opponents and profits from those weaknesses (and DUMB mistakes). You did well. I truly wish you prosperity and good fortune.

But Fellow Americans, the next time your school board proposes to build that brand-new gym because "We Need It", when the old one is serving the purpose well (but it ain't Pretty enough), and in the same meeting, votes to close out the Shop courses, think how many ball Players make it in the big time. (.0005%?) And, think about just who will be making the goalposts, the machines needed to maintain the playing field (bet it isn't the USA!) and how much of that gym's steel was imported.

And, USA, PLEASE wake up!

William F. Wood
- Oxford, Alabama




Q. It appears that the original question was lost in the ensuing (and well stated) responses.

Can stainless steel be colored in a biochemically compatible way?

Yes! Interference colors can be developed on the surface of the material, and without minimizing the underlying brilliance of the stainless steel. These colors result from a phase shift in the incoming light source, much the same way as sound modulations occur when two notes are played that are slightly different in pitch.

I wish you well in your chosen field.

JimC

Jim Clasquin
- Colorado Springs, Colorado, USA
2008


thumbs up sign Thanks for the fine technical answer and the kind words, Jim.

Regards,

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey


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