Anodizing of stainless steel

A. Yes, it can be done. It does not have quite the usefulness that aluminum anodizing has. Two vendors at this site have processes for it. Prismatic Stainless Steel [from B&M Finishers, a finishing.com supporting advertiser] and another that I cannot remember; you can use the search engine [Ed. note: the other vendor was Russamer Lab, and Anna responds below].

A. adv.
Yes, we can anodize stainless steel to different colors, including black.

However in comparison to titanium anodizing, stainless steel colors are not so durable ⇩ and require some type of protective coating to become durable.

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A. Both Prismatic Stainless Steel [from B&M Finishers, a finishing.com supporting advertiser] and Russamer Lab [a finishing.com supporting advertiser] say they can offer it in colors. But the term "anodizing", while literally accurate because it is a process involving applying anodic current to the parts, can also be misleading because the process is radically different from aluminum anodizing, which is dyeable and thus offers a very wide range of saturated colors. The color of anodized stainless steel is diffraction coloration like that of titanium anodizing, carnival glass, and droplets of oil in a puddle. Further, when we see colorized stainless steel ⇨
usually the stainless itself was not colorized, but a titanium oxide coating has been applied to it.

A. You can also treat stainless steel with IVD - ion vapour deposition - to give an aluminium coating. You can then anodise it in the same way as aluminium.

A. Hi, Barbara

Brass plating is probably not practical for a cooktop because brass tarnishes very quickly even at room temperature if not protected with a lacquer, and lacquer/clearcoats may not suit a cooktop. Nickel plating is certainly possible, but getting good adhesion onto stainless steel special pretreatments, so not all plating shops will plate onto stainless steel. Porcelain enameling in black, white, or colors is probably what you want; this finish is closer to melted glass on the surface than paint -- very high temperatures are involved. Sorry, I don't know offhand who offers porcelain enameling, but hopefully it was a little help to clarify what finish you might be looking for. Good luck.

Regards,

A. Yes, stainless steel can be anodized in various colors, including gold

A. Hi Joell. Yes, the color of anodized stainless steel is caused by interference as light waves bounce off of the stainless steel and off of the oxide surface. While you can certainly attempt the process yourself, at this point I don't think there is a wealth of public information on operating parameters -- it is still largely proprietary.

Regards,

adv.
I want to emphasize that a long time ago (2003) I posted that our stainless anodizing was not durable in comparison to titanium anodizing (see my first posting in this discussion). It is not true anymore - we have developed stainless coating that provides the same (or similar) range of colors as titanium anodizing (plus black), and the colors are perfectly durable. We have installed this technological process at a surgical instruments repair company.

A. Hi Mark. There are probably other ways to color the trim than anodizing (chrome-look paint, for example), but you might contact Prismatic Stainless Steel [from B&M Finishers, a finishing.com supporting advertiser] and Russamer to see what they say. There are a lot of threads here, and they may not stumble back onto this one soon :-)

Regards,

A. Hi Adam. As a practical matter, forget about anodizing your fishing reel as an assembly. Although almost nothing is utterly impossible, the processes for anodizing stainless steel and aluminum are radically different and each process is likely to destroy the other material unless it was flawlessly masked, which is highly improbable. Perhaps you can drill out the rivets and replace them with screws, either tapping the aluminum or using nuts.

As for whether anodized stainless steel corrodes ...

"Nothing lasts forever but the earth and sky" -- Kansas, 'Dust In The Wind'

... but anodized stainless steel has been successfully used for medical equipment, wall panels, and some other purposes. In your case, however, the stainless does not need to be anodized anyway. Good luck.

Regards,

A. Hi Paresh. Anodizing of stainless steel is certainly possible as you read in this thread. As for steel, it is not a commercial practice, but may be possible: please see thread 37471, "Can plain carbon steel be anodized?"

But please describe what it is that you wish to accomplish, because words like "anodizing" may lead to misunderstanding because anodized steel, stainless steel, titanium, and aluminum have almost nothing in common ... people may see anodized aluminum and say to themself, "yes, that's what I want for my stainless", and find themself totally misled :-(
Thanks!

Regards,

A. Sorry, but the color only results when the coating is limited to a partial wavelength thickness; it is therefore not appropriate for a wear application like a brake rotor.

Luck & Regards,

A. Mahmood,
When questions get added to old threads like this, I don't know how clear it is that the answer probably lies in the replies above.

In this case, see Ted Mooney's reply to Paresh, where he says "Why do you ask? What precisely do you want?"

You say anodizing, and then you say welding, and then you say hot press bonding, all of which are different things. You also mention polymer, which to me means plastic materials. I really don't know what your actual end goal is.

Since anodizing is not normally done on stainless, I think people need to focus less on naming a process they want and more on describing the surface they want to produce.

 Hi Ray. That was excellent advice that people "focus less on naming a process they want and more on describing the surface they want to produce".

I think Mahmood is making a component from stainless steel and polymer, and is looking for some process to do on the stainless steel (possibly anodizing) which will help the polymer (which is attached to it by hot press bonding) adhere better. My guess is that "welding" was just an unfortunately chosen translation and he actually meant "bonding".

Most of the time, including this time, the questions are too brief; if a question is shorter than the answer they want, it's probably an abstract question which is difficult/impossible to answer properly :-)

Regards,

A. Hi Hannes. 316Ti is only about 5 parts per thousand Titanium so (without any actual experience with it) I wouldn't expect it to be significantly different than other 316 stainless steels, but it would be nice if a reader actually did have experience with it. I also have no experience in knife making, but understand that 3XX is not used for blades since it can't be hardened.

But I don't think anodizing of stainless steel is involved in any way with your choices. Good luck.

Regards,

A. Hi Karl. Any coating, including stainless steel anodizing, will quickly scratch off. I'd suggest black powder coating or paint because it's easy to touch up.

Regards,

A. Hi Karl,

If this is made from stainless steel 400-series, like 420 or similar (surgical steel), it is possible to anodize it black and then special final treat it, so the black becomes as durable as hard anodized aluminum. We are working on similar treatment for 300-stainless steel, but not lucky yet.

A. Hi Anna. I'm going to have to somewhat disagree on this one based on the application.

When you are off-roading and you misjudge the size of boulders vs. your road clearance, or you have to get over it anyway, skid plates (optional equipment on most off-road vehicles), allow the whole weight of the car to 'skid' or scrape across the boulders, riding on that plate instead of ripping out wiring, brake lines and other under-body equipment. As Karl says, the skid plate will get gouged, maybe 1/16" of an inch, maybe more -- not lightly scratched; I don't think any finish at all can maintain its color after such gouging :-)

Regards,

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

A. TiCN with PVD technique can give copper-ish (antique like) colour. Actual colour depends on Ti/C/N composition and other deposition conditions. Being a hard coating it could last for some reasonable time depending on usage. But there are many practical issues like pre cleaning, handling & manipulation of the wire in a vacuum chamber, quantity, etc.

A. If hard temper aluminum would work, it can be anodized and dyed to any color in the rainbow, and the anodizing would be fairly durable.

A. Hi Sumit.

If you're doing a couple of custom bicycles, anodizing might be the way -- what grade of stainless do you want to anodize?

But if this is a production situation, are you sure that your interest is in anodizing stainless steel in a golden color? I think depositing titanium nitride on it in a PVD chamber is more common, more robust, cheaper, and offers closer to a true gold look too  :-)

Get back to us please. Regards,

A. Hi Sue. Surely it can be done, but the issue will be the non-affordability of asking a shop to do a one-off job like this. A faucet washer is a 50¢ item but getting a plumber to replace it is at least a $150 job. Similarly, a plating shop can anodize thousands of small items at a time at a unit cost of say 50¢, but doing one would be liable to cost $100.

If you can find a jeweler specializing in Seiko watches s/he can probably find a black clasp for you, and I see a number of styles of black Seiko clasps on eBay ⇦this on eBay or Amazon [affil links] , but I'd guess that the originals were probably PVD coated for durability rather than anodized.

Regards,

A. Hi Rich. I'll alert Anna that you'd like her input, and hopefully other readers will chime in with technical comments. I am not aware of techniques other than anodizing or PVD application of titanium, but you might search the site with the term "inco process stainless", and then use the same term on google.

Sorry, but we can't suggest sourcing or brands beyond Prismatic Stainless Steel [from B&M Finishers, a finishing.com supporting advertiser] and Russamer Lab [a finishing.com supporting advertiser] (why?)

Regards,

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A. It's going to be real difficult to have your stainless steel art anodized after you are done building it.

I suggest using translucent metal dyes instead ⇨

A. Bruce,
Anodizing is pretty rare for stainless. Not sure what you're trying to accomplish.

Nor do I come across that word too often, so let's check what property it refers to: "The emissivity of the surface of a material is its effectiveness in emitting energy as thermal radiation."

I'm going to go with, I rather doubt that anodizing would have any non-negligible effect on the emissivity of 316 stainless.

Bruce,
So what you're saying is the layer of paint is acting as a thermal barrier or insulator, keeping the heat in too much?

Again, my educated guess is that an anodized surface would not be an appreciable thermal barrier. But again, I'm not sure what you're trying to accomplish. As in, what's wrong with just a bare stainless steel surface, brushed, polished, or whatever?

Besides that, if you need to increase heat dissipation, you could build cooling fins into the structure.

A. Hi Bruce. Generally anodizing roughens a surface and increases its emissivity. In the case of aluminum, the emissivity increase due to anodizing is huge. I suspect that Ray is correct that it will be inconsequential in the case of anodized stainless steel, but don't know where to find such data.
Luck & Regards,


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

A. Hi. My guess is you'll be happier with PVD coatings than anodizing if you want gold color. It will be cheaper, more durable, and more attractive.

Regards,

Ed. note: The forum is most useable when discussions are organized by topic so readers can easily find the most relevant discussions. So we moved Mel's follow up questions about gold plating, titanium nitride, etc., to thread 34692 :-)

A. Hi Ameer. I'm sorry that there are so many questions & answers about anodizing and coloring of stainless steel on this site that it can be time-consuming to find them :-)

Prismatic Stainless Steel [from B&M Finishers, a finishing.com supporting advertiser] and Russamer Lab [a finishing.com supporting advertiser], probably among others, offer proprietary solutions. For your "home project", Goran Budija offers one example of the chemical mix and process conditions in thread 33236, although I wouldn't use toxic, carcinogenic chromic acid in my home. You can search the web or scholar.google.com for "Inco process" or "Inco coloring" for more detail on this.

The issue with PVD is that you need a specialized vacuum chamber which more than a a thousand times as costly as most hobbyists would entertain.

Without knowing why you want to do what you want to do, how big the bolts are, how many, where they will be used, exactly what "tone" of gold you are looking for, etc., it is hard to say whether there might be a third and better alternative. But I'd suggest the online pamphlet
"Colouring Stainless Steel" from Euro Inox as a great intro. And Marvin Sevilla's idea of translucent metal dyes might be a great hobbyist idea. Good luck.

Luck & Regards,

A. Try 50 gms phosphoric acid/ 1 lit water solution, 20 minutes immersion, boiling solution (according to patent US2521580A). Hope it helps and good luck!

A. Hi Anthony. Nobody talked about Alodine on this thread. As Ray Kremer suggests, it's probably best to talk about what we are actually trying to achieve with a finish rather than focus on its name because that can lead us down the rabbit hole :-)
Alodine is a Henkel trademark for a chromate conversion coating on aluminum. Stainless steel will not acquire a chromate conversion coating on it ... so I will say "no, you cannot Alodine stainless steel".

But others have said on other threads, roughly, "I have an aluminum component which we put stainless steel threaded inserts into, and then we successfully Alodined it -- by which they mean the Alodine didn't/doesn't ruin the stainless steel portion like aluminum anodizing would do.

Luck & Regards,