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

  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.

Step 1: Materials and Tools

You will need the following:

Household Chemicals:

• White vinegar (any brand)
• Hydrogen Peroxide (3% -- use a fresh bottle)
• Table salt (any kind will do, doesn't have to be sea salt)
• Degreaser (any brand)

Tools:

• Measuring cup
• Measuring spoons
• Spray bottle

Step 2: Safety First

You will need the following safety items:

• Safety goggles (enclosed type for chemicals not open type)
• Chemical resistant gloves (available at home stores)

First the usual disclaimer: I will not be held responsible or liable for what you do with this information. You are ultimately responsible for using this information in a safe, conscientious manner and for not using it irresponsibly. This information is for instructional purposes only, in the spirit of sharing, and is not intended to be misused by wise guys for practical jokes, or used by people who shouldn't be handling chemicals in the first place. Young children should always have adult supervision when using any chemical. Never use chemicals when medicated (legally or otherwise) or under the influence of alcohol. These instructions are intended for, though not necessarily limited to, people with an artistic bent who just might want to rust something made out of iron or steel.

You will be using an acid, vinegar, and an oxidizer, hydrogen peroxide, so do wear the safety goggles and gloves. Be careful where you spray the solution. It is mildly corrosive and will rust anything made of iron or steel. Do this outdoors preferably in a place sheltered from the wind and away from people or pets. Do use common sense and follow common safety practices. Do not spray chemicals at anything other than the object you are trying to rust. Obviously don't spray it anywhere near people or animals. Don't breathe the vapors. They are irritating. Don't get it near your eyes or anyone else's. If you do get some in your eyes, go and rinse your eyes with cold or lukewarm water immediately. Although the chemicals used are relatively safe, common sense should prevail. If you do not possess common sense, please don't try this at home, or anywhere else for that matter.

Now that we got that out of the way let's get started.

Step 3: Degrease the Metal

I am assuming you already have a clean iron/steel object that is free of any paint or other protective coating. If not you need to strip the finish first before performing this step. I won't go into detail about how to do that since that information is readily available. Read the label on the container of paint stripper if you use that. I used paint stripper to remove the sun-baked paint from my bell. I had to give it a second treatment to remove all traces of paint. I used a paint scraper to remove most of the paint but the paint around the rust spots required the use of an abrasive pad, wetted with the paint stripper, and a lot of elbow grease. Obviously wear goggles and gloves to do this. Nasty stuff.

Once you have clean metal you need to degrease it so chemicals will penetrate the surface. Again wearing goggles and gloves, apply degreaser according to instructions on the bottle. Be sure to remove all dirt and grime as well as oils from the metal. Rinse it well to remove all traces of degreaser. Rinse your gloves well before handling the degreased metal. You don't want to add back any dirt or oil. Don't touch the metal with bare hands or you will make oily fingerprints which might show up on the final finish. Now take your objet d'art to the outdoor place where you will spray it with chemicals.

Picture below shows clean degreased metal ready for the next step.

Step 4: Pickle the Metal

This step is critical so don't skip it unless you actually want non-uniform rusting. At first I didn't do this and several areas would not rust because the solution could not penetrate the surface of the metal. You can see this in the picture below. I simply hung up the degreased bell and sprayed it with solution. You can see where the solution did not penetrate. Those areas did not rust at all. I then pickled the entire bell and after I did it rusted all over.

Believe it or not, you can pickle metal with the same ingredient that is used to pickle cucumbers. Yup, you guessed it, vinegar. Place your object where you can spray it from all sides, away from anything you don't want to get sprayed, including people, pets, and other objects. Put on your safety goggles and gloves. Put some vinegar in the spray bottle. Not too much, just enough to cover the object several times. Spray the object from top to bottom all around. Soak it good. Let dry and repeat several times. The more the better. Placing the object in direct sunlight will speed drying. The acid in the vinegar will etch the surface of the metal so chemicals can penetrate. If you skip this step and proceed with the next step or don't like the results of the next step, just come back to this step and spray again with vinegar. The acid in the vinegar will dissolve most of the rust. Don't worry about it. This is normal.

That's it. Now we're ready for the fun part.

Step 5: Rust the Metal

Now for the step you just can't wait to do. This is the exciting part.

Wearing your safety goggles and gloves, mix up a batch of rust accelerator adding ingredients in the order given:

• 16 oz Hydrogen Peroxide (use a fresh bottle)
• 2 oz White vinegar
• 1/2 Tbsp Salt

You can use any of the pickling vinegar that is left over from the previous step. You can mix this accelerator solution directly in the spray bottle if it has a wide mouth or you can mix it first in the measuring cup, making sure to dissolve the salt, and transfer it into the bottle with a funnel. By the way I did see recommendations of up to 8 oz of vinegar but I tried that and it didn't really work as well as 2 oz. You can experiment with the proportions but this worked well for me. Same with the salt. It won't hurt to add a little more but again, this worked for me. Tighten the spray bottle cap and shake well to dissolve the salt.

I assume you have placed your awaiting object in a safe place away from people, pets, and things you don't want to get rusted and by now you are dying to see some rust. Are you ready? OK. Let's go.

Spray some solution onto your object, soaking it from top to bottom all around. Now sit back and watch the magical transformation. It will start foaming and begin to rust before your eyes. Is that something or what? If it doesn't rust then you didn't degrease it enough or you didn't pickle it enough and will have to repeat one or both of those steps. Another possibility is the temperature is too cold. This works best at elevated temperatures. It is best to let the object sit in direct sunlight and heat up a little. Let it dry and repeat. I only had to let it dry for 5 minutes but YMMV (Your mileage may vary) depending on the ambient temperature. The rust patina should deepen each time you repeat the spraying and drying cycle up to a point beyond which there is no noticeable change. Keep spraying and drying until you are satisfied with the degree of rusting. I repeated the cycle about 6 or 7 times but again, YMMV. The pictures show the progression of the rusting process.

Congratulations! You have greatly accelerated a natural process and now have a piece of metal with an attractive aged-looking patina.

Step 6: Finishing Up

I would advise you to dump the remaining accelerator solution from the spray bottle and rinse the bottle and spray head well with clean water. Then spray some water through the head. This will help prevent the spring inside from rusting. You can save the solution in a jar with a plastic, not metal, top if you like, or just dump it in the toilet, flushing immediately, or in the sink, flushing it down the drain with lots of water.

Now you have several options. Be careful not to touch the surface of the rust. It is very delicate right now and powdery and can come off by rubbing. Not all of it but enough of it. You can go hang it like I did and let mother nature take over. The last picture shows the bell after a torrential downpour and subsequent drying by the sun. You can see that the color deepened from an orange color to a deeper brown color. The grain is also coarser. Or you can spray it with a fixative like acrylic or polyurethane spray. Some people recommend rubbing it with salad oil. I wouldn't, because, first, it would be messy, and second, salad oil will become gummy after a while. Mineral oil would be preferable but still messy.

And that's it. Wasn't that easy? One note. As I mentioned, my bell is made of COR-TEN steel, which is designed to rust on the surface to prevent any further rusting. Other steels are probably different in the speed at which they rust and may require more or fewer spray/dry cycles. I hope people will report their experiences in the comments section. Now that you know how it's done, go and rust something and tell us all how it came out. Have fun.

Comments

[Craig FaustusB]

I have some corrugated weathering steel. If I don't do anything but water it daily, how long will it take to rust?

[MarkI36]

This How To would be much easier to follow in a larger font size and using paragraph spacing to separate concepts. At 100 characters per line, it is difficult to find the start of the next line with such long paragraphs. Instructables tends to not instruct about how to post information in a readable format. 60 to 70 characters per line is the max for a readable article. 6 to 8 lines max per paragraph helps readability.
For example:
[Spray some solution onto your object, soaking it from top to bottom all
around. Now sit back and watch the magical transformation. It will start
foaming and begin to rust before your eyes. Is that something or what?
If it doesn't rust then you didn't degrease it enough or you didn't
pickle it enough and will have to repeat one or both of those steps.
Another possibility is the temperature is too cold. This works best at
elevated temperatures. It is best to let the object sit in direct
sunlight and heat up a little. Let it dry and repeat. I only had to let
it dry for 5 minutes but YMMV (Your mileage may vary) depending on the
ambient temperature. The rust patina should deepen each time you repeat
the spraying and drying cycle up to a point beyond which there is no
noticeable change. Keep spraying and drying until you are satisfied with
the degree of rusting. I repeated the cycle about 6 or 7 times but
again, YMMV. The pictures show the progression of the rusting process.]
Reads easier reformatted.
[Spray some solution onto your object, soaking it from top to bottom all
around. Now sit back and watch the magical transformation. It will start
foaming and begin to rust before your eyes. Is that something or what?

If it doesn't rust then you didn't degrease it enough or you didn't
pickle it enough and will have to repeat one or both of those steps.
Another possibility is the temperature is too cold. This works best at
elevated temperatures. It is best to let the object sit in direct
sunlight and heat up a little.
Let it dry and repeat. I only had to let
it dry for 5 minutes but YMMV (Your mileage may vary) depending on the
ambient temperature. The rust patina should deepen each time you repeat
the spraying and drying cycle up to a point beyond which there is no
noticeable change.
Keep spraying and drying until you are satisfied with
the degree of rusting. I repeated the cycle about 6 or 7 times but
again, YMMV. The pictures show the progression of the rusting process.]
Much easier to read.
btw, The etching removes an oxidized surface called Mill Scale. It is oxidation that happens as the red hot steel cools during processing at the MILL. Mill scale rusts very slowly.

[Archibold]

hi, nice post.is
that using "


Food Grade Hydrogen Peroxide 3%" ?or is there other grades and percentages that
should be used?

[AlisonF31]

Thank you. It worked well on mild steel sheeting. I degreased the steel and painted this with enamels. when the enamels were dry I carried out the rusting process. I was able to achieve the amount of rusting I needed. The enamels were not damaged. I finished off with a wax polish. The sort that is generally used for wood.This gave a lovely soft finish.

[SteveKenyon]

Hi - I have started a new signage project, the sign tray and its frame are constructed from fresh coreten, I want to get the lovely rich patina before installing but have a query I'm not sure if anyone can help with. On the face of the steel will be cut acrylic letters which will be VHB taped on. I'm thinking that this should be done whilst the steel is fresh and clean but concerned that the accelerator solution will strip away the glue from the tape. I have a few "swatches" to test it first, but if anyone has any thoughts or ideas to throw into the mix I would be very grateful! - Cheers

[RandW3]

Thanks for the info. I used muratic acid to etch the surface first instead of vinegar. I got amazing results.

[makieme]

I've been using your method and love the orange patina achieved by submerging the steel in the mixture. However, I'm finding it creates an excess amount of rust dust later. Is there a non toxic way to stop this process? I can't clear coat as I'm working with far too many pieces. The other look I love is the acid wash look (similar to SusieL15), which I believe wouldn't cause all of the dust. However, I don't want to use chemicals. Do you have any advice? Thanks!

[SusieL15]

Thanks for the easy to follow instructions! I've used it on letters for barn wood signs and LOVE the look!

[makieme]

Hi Susie, looks great! How did you achieve the variegated look?

[Laral]

Looks great! I like the variegated look. It looks more natural.

[JorisK2]

Thank you for the detailed explanation! I used the steps described to accelerate the rusting of bended Corten steel metal and made a timelapse video of the process. Perhaps it is of use to anyone:

[Laral]

Thanks for the video!

[DELTA_117]

Hey, this is really great, thanks for that! I want to achieve this look, I was wondering if you would recommend against doing this for (what I think is) a steel helmet from a functional perspective, just in terms of something that gets handled a lot, assuming it can be done at all. My thinking was to do this, and then apply a fixative as you said. Thanks!

[Laral]

Sorry for the delay. I haven't been getting notifications for comments.

I see no reason not to do it. Keep in mind, it will be powdery at first and comes off easily. A fixative is good or you can let it stand around a while and let nature take over. You could spray it with water every day to accelerate the process.

[fitterman]

What's the best way to dispose of any excess fluid? I made a little more than I can use and don't feel comfortable pouring it down the drain. (By the way, the method worked incredibly well!)

[scienceinquiry]

3% hydrogen peroxide is mildly basic, so a weak acid (vinegar will do) will neutralize it...if you use a strong concentration, 30% that would be bad, therefore again neutralize it slowly as this will render lots of heat, add SLOWLY with ample SAFETY equipment until all reaction is complete...this is best done with small amounts rather than the whole enchilada

those wanting to neutralize acids, baking soda is highly recommended using the same process

[Laral]

I don't know. I think such a dilute solution flushed down the toilet with a much larger volume of water would cause no harm to the plumbing or the environment. You wouldn't hesitate to flush any of the very mild ingredients individually would you, so why worry about them in combination?

I'm glad you had such success with the formula.

[fitterman]

My only concern is that it's mildly corrosive so I would hate to ruin any of the metal pipes in my home. Sounds like attempting to dilute it is the best plan.

I should add that overnight the rust on my planter bloomed into a wonderful result, even better than when I posted my question.

[ezliving]

Hello, I am using this formula ( mostly, maybe a bit stronger H202) and am loving the results so far. Will post first photo and when done will post another. I started with a sandblasted fire pit and then added coats.

[ezliving]

I have placed it and am hoping it will age gracefully, without being disturbed too much until it set's up. Will probably have a few camp fires in the meantime. Thanks for all of the great info that helped get me hear..