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Produce a Rich Rust Patina on Iron and Steel, Safely and Quickly, Using Common Household Chemicals

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  This instructable will show you a fast, safe method, using common household chemicals that you probably already have, to produce a rich rust patina on iron and steel to give it a weathered, aged appearance.

Background

I've had this Maine 'buoy bell' wind chime for about eight years now. I really like it. It has the haunting melancholy sound of a bell buoy at sea being tossed by wind and waves. It is made of COR-TEN steel which is designed to rust on the surface to create a protective barrier against further rusting. It came painted black on the outside and was supposed to develop this rich rust patina naturally over time. Well, the unpainted inside did rust completely after about a year, but the outside only rusted slightly, near the bottom, even after exposure to the sun, rain, and snow of the northeast for eight years. I wanted it to have a nice rust patina that looked like it had been hanging on the eaves of a lobster shack, at the end of a pier, for many a year, being splashed and buffeted by nor'easters and sudden gales. Seeing it was taking so long, I decided to take things into my own hands and, ah, "help" mother nature along and accelerate the process. I searched the net and found mostly dangerous methods to induce rust on steel using highly caustic or acidic chemical solutions. However I finally did find a simple safe method, using on-hand household chemicals, buried deep within a thread on the subject at a metalworking forum. I got spectacular results which have not only withstood the wind and rain of the southwest but have actually improved with the help of mother nature. I like the results so much, and there is so little practical information on the subject that is accessible to the general public, I thought I'd share this simple method with the instructables community.

Judging by the number of posts on forums asking how to do this, I see I am not the only one who wants to actually promote, rather than prevent, rust on iron and steel objects. I found out the basic information for doing this at the very cool ArtMetal forum: http://www.artmetal.com/blog/bob_turan/2009/04/rust_promoter . I'm guessing that there are more than a few instructables members who have a similar desire to prematurely age some iron/steel artifact, so I encourage people to post pictures of their resuls in the comments and add tips on how they did it so we can all learn. This method is not set in stone. Posts about useful variations on the method are always welcome.
 
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Karen1550617 days ago

Does anyone know what chemicals I can use to turn a rusted iron sculpture bluish green? I bought one and it is now reverting back to full brown rust. I am hoping I can brush something on it to bring back the blue green oxidized color.

Laral (author)  Karen1550617 days ago
Hi Karen, I never heard of blue/green rust but I found the following:

Iron Corrosion Products

They produced just what you are looking for by placing a nail in a solution of 12% acetic acid (you can use vinegar which typically contains 3% acetic acid) and sodium hydroxide (dollar store drain cleaner). Not that I can recommend this but, if you try it, be really careful because this will produce an acid/base reaction, probably a fairly violent one. Wear chemical resistant gloves (Home Depot/Lowes) and sealed eye protectors, not the open type. Do it outside, if at all possible, away from anything or any one that could be harmed by it, including especially pets and children. They point out that you have to seal the object during the reaction in order to prevent oxidation from the air--maybe a garbage bag. So it is an anaerobic reaction. I also found out that this compound is stable only in the absence of oxygen so you will have to seal it with acrylic or some other sealer to prevent it from turning brown again.

Interestingly enough, I also found out during my search that there is a book called The Green Rust by Edgar Wallace free from Project Gutenberg. There is also a free audiobook The Green Rust from LibriVox. I think I'll download both and read and listen at the same time. It looks like a good book. :)

Please post some pictures of your results if you attempt this! And be careful…

Thank you SO much for your detailed and very informative reply. The technique sounds more than a bit above my pay grade. ;-) The sculptures are replicas of 2 ft high Agave plants and the guy who makes them green before selling them to the garden shop does not speak english and doesn't seem interested in revealing his techique. Whatever it is , it's not sophisticated because he sprays or brushes it on and sells them by the truck lload. They just revert back to rust after being in the yard a year or two. I will check out your info. Muchas Gracias! Karen
Laral (author)  Karen1550616 days ago

OK, I know exactly the ones you are talking about. Very sharp pointed and lethal looking. Then the guy is probably not sophisticated enough to know how to do that chemically. The cheapest way for him to do it would be to make a wash with some greenish paint and paint thinner and brush that on. That would be cheap and easy for him and would eventually rust out just as you describe. You could touch it up with the right color spray paint. That's what I would recommend doing.

Laral (author)  Laral17 days ago

Here's the image from the site that I couldn't upload before because of server maintenance of this site.

rust-blue.jpg
Laral (author)  Laral16 days ago

Update

I tried this formula out on a nail I rusted, using my original formula to imitate your situation. It did not turn it green. When I went to reapply the mixture, it flaked off pretty large pieces of rust so I would not recommend this in your case.


ehall193 months ago
Hi, I know this post is a few years old but I just found it yesterday and tried it out on my box bike frame and it worked great but the rust wipes right off. Will the rust adhere itself to the metal over time and stop doing this, or will it just stay on the surface? Hopefully I hear back from you. And thanks for this post, I used the exact same ratio you posted and it turned out great! Only prob is that at this point it wipes right off.
Laral (author)  ehall193 months ago

If you can avoid touching it for a while, the rust will penetrate deeper and become permanent. Or you can seal it with acrylic or polyurethane spray.

ehall19 Laral3 months ago
Ok awesome! As long as it will eventually adhere to the metal that's fine. Hopefully it won't take that long. Once it does I'm gonna spray it with some matte clear coat(I hoping/assuming that's what you mean by acrylic or polyurethane spray) to seal it. I bought the frame in bare metal(no clear coat) and as soon as I got it(when it was still all nice and shiny) I put some die cut stickers on it so that once it rusted I would peal the stickers off and the logos would be "unrusted" in to the frame while the rest of the frame would have a nice rusted patina. But it was taking forever for it to rust and when it did start to rust it was really uneven. But your formula worked great!! I'd like to post a pic in this comment to show you how it turned out but can't figure out how to do it. Anyway, thanks a bunch!
Laral (author)  ehall193 months ago

It could take some time to develop a thick layer of natural rust. Wet it often and leave it in the weather. You could just clear coat it right after you rusted it but a thicker natural layer of rust would be more resistant to scratches. Please post photos, this sounds really cool. Isn't there an 'Add Images' button below the edit box? You need to enable javascript.

ehall19 Laral3 months ago

finally figured out how to upload the pics hahaha!! I haven't taken the stickers off yet cause I'm waiting for the rust to adhere itself to the metal a little better.

image.jpgimage.jpgimage.jpg
Laral (author)  ehall193 months ago

What's on there, one application of rusting solution? Did you clear coat
it? Why not go all the way and rust the handlebars, clamp, and fork, and maybe the pedal cranks? It would look
great. You'd have to strip the paint to bare metal and sand and degrease
it thoroughly, which I assume you did for the frame.

ehall19 ehall193 months ago
*bmx bike frame not box bike frame hahaha!
ecanod10 months ago
The receipe works and will produce a rust patina. However, when applied on weathering steel (aka cor-ten, which is a brand name) the resulting patina will not have the protective properties of a real long-time natural patina. The protective properties of the rust formed on weathering steel depends on the microstructure of the patina. The composition is basically the same as in plain carbon steel, but not the morphology.

In order to form , a protective patina on weathering steel needs to be formed naturally, by exposure to humidity/dryness cycles and to a mildly polluted environment. Too much pollution (which is basically what you are adding to the surface with chlorides -salt- and acetic acid -vinegar-) and the patina will not form properly to be protective.

So, accelerate the corrosion if you like the appearance, but don't expect it to be protective. And don't waste your money buying cor-ten stell if you are going to artificially produce the patina: buy cheaper plain carbon steel, the result will be the same.
Laral (author)  ecanod9 months ago
This all may be true but it is largely irrelevant to this application, which is to produce a beautiful rust finish, not a protective seal. Note that I did mention that the rust is a dry powder that might require a fixative if it will be handled by any one. Someone in the comments did just that. Even if you were to rub off all the surface rust, there would still remain a fine rust patina. In any case, this accelerates the production of a protective finish as well by initiating the process. It would take years to accomplish what this method does in minutes. Once started, the process will continue naturally by exposure to the elements. As far as wasting money buying cor-ten steel, first, that happens to be what the manufacturer of this particular bell chose because of its aesthetic qualities and its durability, second, it's not that much more expensive, and third, it will have a long-lasting fine patina.

BTW, I've included a shot of the bell 4 years later. Note the fine-grained texture of the PERMANENT patina that is the result of natural oxidation.
IMG_1951_cr.jpg
Hi again. I wondered if you had any advice about if i can 'water down' the mix in the spray bottle. I am working on a mirror which is not just a flat piece of steel. It has a patten welded on with leaves etc. When i spray the chemical on, it collects at the corners and under the leaves. This then leaves an uneven colour and slightly flaky rust in places. If i put more vinegar into the mix would this 'water down' the mixture and make it easier to spray??? Or will the colour even out when i spray it with polyurethane? Any other suggestions would be appreciated.
Laral (author)  wroughtirondesigns9 months ago
You could dilute it with water I suppose but the unevenness adds to the natural look of it. If you look at natural rust, it is uneven like you describe. I wouldn't add more vinegar. Polyurethane is just a fixative to protect the final finish.
asafweis10 months ago
I'd like to use this method to rust a steel fence made from round rod poles 12mm in diameter. Can anyone tell me if the rust will come of on your hands if you touch it?
Laral (author)  asafweis9 months ago
As I mentioned, initially the rust is a fine powder that will come off on your hands. If you leave it alone, the rust will continue to build up on its own. This process initiates and accelerates the natural process considerably. You could spray it with polyurethane but that would retard the natural oxidation process.
Knyman11 year ago
I have been thinking of ways to used the bi metal food cans and wondering if a patina process can work on them. Also, what if I don't want a completely rusted look - some color on them...like your pickling process picture where there is some rust and some blue. Any thoughts?
Laral (author)  Knyman11 year ago
Just sand the parts where you want rust.
bajareke1 year ago
Simply amazing..! I have been looking for a simple, fast and environmental friendly method to patina some of my works and... wow! I found it. Thank you for such of a clear way to explained. Funny too.
I want to add my experience with this method. I live in south Florida where sun heat is good, but I wanted to accelerate the drying process and applied extra heat with a propane torch: unexpected and beautiful results. Then I applied a few times more of the solution recommended and dry it again with the torch, obtaining (depending of the heating time and distance from the piece) different shades of brown. Also I sprayed on the plate (by mistake) black spray paint, and kept working with the torch and adding solution and drying it, obtaining excellent results.
Note: protect yourself with a proper mask for any possible fumes, aside of the rest of the recommended protection. I was working on 1/8 regular steel plate. At the end I sprayer with clear protector for metal and sanded to diminish the glossy finish. See the results!
Picture 4.pngPicture 3.pngPicture 2.pngPatina 1.png
Laral (author)  bajareke1 year ago
@bajareke:

Wow, that looks fantastic! I will try that next time I need to rust something. And thanks for the kind words.
I am wondering if at stage 5, if you rinse off the rust accelerator at anytime. I cannot get my spray bottle to spray it on, so am applying with a large paint brush. The rusting process is happening, but leaves quite a residue on my work.
My first attempt i washed it off and the rust came off with the water.
Any suggestions?? I wish to rust a steel item quickly, and finish it with a polyurethane spray.
Laral (author)  wroughtirondesigns1 year ago
You should not rinse it. Let it dry. Don't touch it. It is very delicate at this stage. Once dry, you can spray it with poly. Work on getting your spray bottle to work. It gives much more even and controllable results.
It did work for me in a great way,thanks a million.
That is so cool! I was shocked at how fast it rusted!
I am going to post a pic on my website for people to check it out. It is the 32 ford custom coupe. www.Metalartpro.com
FOOLPROOF !!!! thank you so much !!!
Laral (author) 2 years ago
Holy cow, I can actually see all my steps at once AND download a PDF of them! It looks as if all my rants have paid off. LOL. Thank you for (somewhat) restoring my faith in my fellow man (and woman). ;-)
I feel compelled to indicate that the "Rust Accelerator" solution is essentially peroxyacetic acid. This is a corrosive and possibly harmful chemical which can damage the airways and in strong concentrations can be hazardous.

It is created by mixing the hydrogen peroxide with the vinegar.

https://en.wikipedia.org/wiki/Peroxyacetic_acid

I'm not saying it's not a great idea, but I'm saying be super careful not to get it on your skin. It's extremely corrosive and will probably destroy plastic it is stored in over time. It works well for rusting things because it oxidizes whatever it touches at an accelerated rate. Including skin. So I might not agree in saying this is SAFE. SAFER, perhaps, than using more frightening chemicals, but...
Laral (author)  BenderBendingRodriguez2 years ago
First of all, see all the cautions given in Step 2 Safety First. While I didn't identify the compound that you ferreted out via Google, no doubt, which, according to the article you cite, is more commonly called peracetic acid, I gave a description of essentially the same properties mentioned and precautions for dealing with them. That said, you are obviously not a chemist, and neither am I, but I know enough college chemistry to know the difference between concentrated acetic acid and vinegar (5% acetic acid), and between concentrated hydrogen peroxide and the 3% household variety. Note also that I am not advising anyone to do what the article outlines: "Peracetic acid is produced by continuously feeding acetic acid and hydrogen peroxide into an aqueous reaction medium containing a sulfuric acid catalyst." The solution produced by these common and safe household chemicals is obviously no where near the concentrations produced by this industrial process. I also note in the article that "Peracetic acid is an ideal antimicrobial agent due to its high oxidizing potential. . . . It also breaks down in food to safe and environmentally friendly residues (acetic acid and hydrogen peroxide), and therefore can be used in non-rinse applications." and "The United States Environmental Protection Agency first registered peracetic acid as an antimicrobial in 1985 for indoor use on hard surfaces. Use sites include agricultural premises, food establishments, medical facilities, and home bathrooms." Also, "Exposure to peracetic acid can cause irritation to the skin, eyes and respiratory system and higher or long-term exposure can cause permanent lung damage. In addition, there have been cases of occupational asthma caused by peracetic acid." I clearly advise measures to be taken against the first 3 of these exposure hazards. And I clearly don't advocate "higher or long-term exposure" which obviates the risks of the 4th and 5th symptoms. As for any possibility of this solution destroying plastic, have you ever seen a gallon of muriatic acid, available in hardware stores? It comes in plastic jugs. It is far more corrosive than this very weak solution of peracetic acid. So, in conclusion, although you may mean well, as the preacher sayeth, "We A-L-L know what road is paved with good IN-TEN-SHUNS!" Let's be honest, you really didn't read the article you cited very carefully, and you jumped to highly unlikely conclusions. Yes, be careful if you make this stuff. If you follow my instructions--and the dictates of common sense, you should have no problems. If not, you are on your own. . .
Great work. It worked like a charm for me on some screws for a more rustic look.
Laral (author)  wright.or.wrong2 years ago
I'm always glad to hear of how someone used this. Thanks.
fzumrk2 years ago
If the metal you would like to rust is galvanized, you can remove this with the 'pickling' step. I have been de-galvanizing screws to use in restoration projects with a bath of 90% vinegar/10% lemon juice. I just leave the screws submerged in the solution overnight and rinse them off when done. I let them air dry afterwards and they get just a little bit of rust on them. You may want to degrease them first, but I have skipped this step and it has still stripped all of the galvanizing.

Note that the stuff I have stripped is likely electroplated or cold-galvanized. I haven't tried anything with a heave hot-dip galvanized coating, but it probably takes longer to dissolve all of the zinc.
doomsdayltd3 years ago
d@mn i shouldn't of bought my rust type paint, this does the exact same effect for 6 dollars when i spent like 16 for the real rust paint :(
Laral (author)  doomsdayltd3 years ago
Rust paint? What is it, rust-colored paint or paint that promotes rust? How did you spend $6 using this method? You must have rusted a battle ship. :)
well what the rust paint does is it puts a layer of paint with iron oxide in it, then the other solution you put on promotes rusting of the iron oxide. and yes this method is only like 6 dollars since how inexpensive the items were for this.
Laral (author)  doomsdayltd3 years ago
I guess if you bought everything from scratch it might be $6. I had every item on hand so, in a sense, it didn't cost me anything because those items were already being used for other purposes. Just the negligible cost of the ingredients.

I didn't know there was such a thing as that paint but this way must be cheaper than any commercial product. I also found a very cheap way to produce a nice green patina on copper and brass. the commercial products to do this are outrageously expensive.

cr.jpg
gypsyloot Laral2 years ago
Hi Laral- your details were really helpful to me, so glad I came across this. I didn't notice if you posted your "cheap way" to produce the green patina ... if you're able to I would very much appreciate it!! ... thanks ;-)
Laral (author)  gypsyloot2 years ago
Have a look at:

http://asuwlink.uwyo.edu/~metal/patinas.html -- the second formula.
I got a sal ammoniac block from Ace at the time but I don't see it now at their website. I found that eBay has ammonium chloride powder cheaper than what I paid for the block. It would also dissolve much easier than the hard block.
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