Instructables

Preserve the Beauty of Raw or Rusted Steel & Iron Surfaces

Picture of Preserve the Beauty of Raw or Rusted Steel & Iron Surfaces
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I see many ibles made with black pipe here but rarely do they mention any coatings to prevent rusting. I also often build with rusty items where I need to cover the rust so it won't rub of on clothes etc. but don't want to lose the beauty of the patina. An architect once told me he used linseed oil to preserve rusted iron outdoors. I tried it but the damned stuff never fully dries! I could use polyurethane but the oxidation will continue underneath and it will eventually flake off. I've tried "rust stabilizers" but they turn the rust black so it loses it's color. I finally got turned on to a product from an old timer in a paint store I would probably never have found on my own.
 
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Step 1: Penetrol

Picture of Penetrol
He recommended a product called Penetrol normally used as a paint additive to improve flow and adhesion that also seals and stops rust. It can be used alone as a base coat on bare metal and will fix the rust while preserving the appearance. The finish will be darker than dry rust but similar to rust sprayed with water or oil and can be top coated with a polyurethane for a more durable finish.

http://www.flood.com/paint-additive-solutions/products/view-product.jsp?productId=11
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I would say that Penetrol is most likely based on linseed oil. There is just no other oil that has those properties. Why yours didn't dry was because it wasn't coocked/boiled or of a lesser quallity.

I never had that problem with penetrol. That was with an early project with linseed oil where I didn't know I needed BOILED linseed oil. 12 years or so later, that lamp is STILL a little sticky. The penetrol works fine but it's not a very hard surface. That's why I top coat it with poly.

I didn't say Penetrol would give the same result as raw linseed oil. I just said that Penetrol most likely consist of boiled linseed oil. This due to what it is said to achieve. There are very few oils that has those abilities. As I own a large producer of linseed oil I have some understanding of where and how it is used.

Ive not seen a Matte Polyurethane spray. Would a satin work? Im trying to preserve some decorative Roman Armor pieces. I don't want them to rust through and currently I have to keep them oiled which I would much rather not be doing.

BrianJewett (author)  Tr0ublesome8 days ago
If they're repros, then yes, this should work. If they're actual Roman antiques, talk to a conservator for professional archival techniques.

If there is no rust, you can clean the oil off and go straight with the polyurethane.

Thank you sir! I appreciate the info.

I have some small steel tags I would like to make bracelets with...the steel tag will be personalized with metal stamps and attached to a leather band. The tags are raw steel. Is there anything you'd recommend to prevent rust for small steel tags used in this manner? Thanks in advance for the advice!!

Anyone have any ideas??

Shoot. I already replied to this but it seems to have evaporated. I guess I screwed something up.

My first suggestion would be to not use raw steel. Aluminum, brass, stainless steel, silver or gold won't need coatings. There's no coating that I know of that would stand up to the wear this would receive. If you choose to ignore this advise, (you should always ignore advice like this ;-) then I suggest you experiment with a few pieces for yourself before gifting or selling any. My first try would be to make a piece without coatings and see how it ages or wears. If you keep it dry and wear it continuously, it might develop a nice patina on it's own and the oils in your skin might be enough to protect it. You could do another piece and coat it with pure carnauba wax or Johnson's Paste wax. This would need to be re-waxed every month or two.

You could also try heating one with a torch and dipping it in oil while hot. This could be dangerous so find out the right way to do this and what kind of oil to use first. I have no experience with this but I know there are ways to heat treat steel for a blackened or blued surface. These would still need to be oiled or waxed to prevent rust long term but wearing them everyday might be enough to keep them nice.

In the end, you'll just have to play around and find out. You could also check on some jewelry forums. I haven't seen raw steel used in jewelry but jewelry people may know something.

Good luck, and let us know if you learn anything useful.
cjh33318 days ago

I have 8 steal panels 15.75 X 26 inches-- each piece will have various cut outs that when viewed is smooth with various designs on one side and sorta rough on the other. The 8 pieces of steal will hang over the exterior deck and subject to the weather. The side of the steal facing the deck will have a patina chemical finish. I am researching the best method to clean the steal, and prepare the surface for the patina chemicals then preserve each piece the deck side with the patina (any advice appreciated). Murratic acid and mineral spirits before the patina chemicals is today's plan.

Both sides could have and application of the penetrol --- but after reading this blog a ploy aplication on the side facing the deck would likely peal over time so re- applying the Penetrol as needed would be a correct method.

The side facing the sun can have an application of the followed with several coats of poly -- If the poly peals I would rather re-apply as needed for the areas that face the deck --- Is that right?

BrianJewett (author)  cjh33318 days ago

This is also way outside of my experience. I haven't even done any outside pieces. If it was me, I'd just make sure they were hung so they don't drip on anything you don't want stained and then just let them rust naturally. Personally, I wouldn't mess with the artificial chemical patinas.

BrianJewett (author) 1 month ago

I don't know much about shellac but what makes it less toxic? Isn't it mixed with mineral spirits (paint thinner)? Polyurethane is pretty stable once cured. It's a much more durable finish than shellac and may be less toxic in the long run.

Shellac comes mixed with denatured alcohol which, while toxic itself if inhaled/consumed, evaporates off almost immediately leaving only the resin. If you buy the flakes you can mix your own using everclear if you can find it. It's not nearly as durable as poly (though it is more moisture resistant) but would probably suffice for something that doesn't get heavy use.

Shellac is not toxic. It is the least toxic of any finish. It was once used to coat candy and pills. It is mixed with denatured alcohol, not mineral spirits. Polyurethane is much more durable but in my opinion, shellac has a much better feel and look than polyurethane. At least on wood.

Love all the info. Do you think I can substitute the polyurethane for shellac? I make art from wood and rusty metal and would rather something less toxic as a final coat.

kesellers11 month ago

Hi,

I have found your post while trying to figure out how to treat table legs I will be creating. I am going to use black steel pipe from the hardware store to create table legs with butcher block top (see example picture). The legs will not be exposed to liquid, and they will be indoors, but the man at the hardware store gave me the impression they could still rust. He suggested I use some type of wax, but he wasn't specific. I do have small children so I need the legs to be safe for them and it will be pushed against my light colored sofa so it can't be anything that would rub off and stain. Should I just clean them well with steel wool and then use poly or should I use the Penetrol product you suggested? Thank you so much!

BrianJewett (author)  kesellers11 month ago
I've built several things with black pipe. I've always just wiped them down with mineral spirits (paint thinner) to be sure they're clean and then sprayed them with a few coats of flat polyurethane. I've been using a towel bar for over 4 years daily and it still looks like the day I hung it.

I used Johnsons Paste Wax for a steel bookshelf I built. It's good after 3 years but it will probably need re-waxing periodically. It's not as durable as the poly and it would not work well on the threads and fittings.
Thanks so much!!

My picture didn't work, but I think you get the idea. :)

seahouse2 months ago

We have a staircase with steel stringers that is installed in the home we are building. Railings too. The stringers have rusted more than we expected since they was first installed, but the rust has grown on us. Would you recommend using penetrol to stop the rusting and then waxing after that? The rest of the home is close to finished, so it's a little late for a polyurethane coat. We talked to a painter and the quote was a lot more than what we can do right now. Would the waxing keep rust from getting on people's clothing if they lean against the steel? Thanks for any advice!

BrianJewett (author)  seahouse2 months ago
Use the polyurethane. It may be stinky for a few days while it cures, but it's worth it. Wax can be used indoors on a bare steel surface that's not rusted but it wouldn't work over rust and I'm not sure it would work over the Penetrol. The polyurethane can go on over Penetrol and I'd recommend using it at least on any wear surfaces like the railings. It's much harder and more durable than the penetrol on it's own. The Penetrol is basically boiled linseed oil with hardeners and anti-rust additives. It's fairly soft and won't wear well but it's OK on it's own for surfaces that don't get rubbed.
vzdz2 months ago

Hi Brian,

I built a steel fire pit for a client with the intention of letting it rust and sealing it to preserve that rusted color. Well, It's sat in the salty coastal air for a year and the color and texture are now perfect. I'd like to use the Penetrol method, but my question is, will poly be a durable and uv stable enough top coat? I've read that automotive clear coat works real well, too. Any thoughts?

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BrianJewett (author)  vzdz2 months ago
If it's fairly heavy steel, I'd just leave it raw. I don't have any outdoor experience as my pieces have all been indoors, but I don't think the coatings will do well with fire. I think someone else hear said it needed re-coating after a year or so outdoors. The rust will scale over, slow down and get even better looking with age. If it's 1/8 inch or better I'd say leave it alone. It will probably outlast your client as is.
skaphan5 months ago

I have some exterior steel doors and trim at my house that is (deliberately!) rusted and that we occasionally coat with Penetrol. The problem is the Penetrol wears off after awhile and then the rusting process starts up again. If you don't stay on top of it it starts scaling and looks bad. Do you think polyurethane would make sense for an exterior application? I'm thinking it might be better to just recoat it with Penetrol every couple of years. I'd hate to have to try to remove polyurethane to refinish it. Or maybe we should use some other type of clear mat coating other than polyurethane?

I have tried many finishes for steel, interior and exterior, and the best i have found is a combination of Penitrol, Carnuba Wax, boiled linseed oil and a little bit of mineral turpentine.

BrianJewett (author)  steamjunkprops5 months ago
Combined how and in what proportions?

Has this worked well in outdoor applications?
BrianJewett (author)  skaphan5 months ago
I haven't tried an exterior application with poly on metal but I haven't had good long term success on wood. I'd try checking with a paint expert. Not at home depot but a good pro store like a Sherwin Williams. If you get a good answer, post it here and share with the rest of us.
crob15 months ago

Hi Brian,

really like the work you did. The info about the penetrol was very helpful. I have an old military metal (fire proof) dresser that i grinded down to get some of the old paint and damaged spots off of it. I messed up and tried a polycrylic on it, but it was a disaster. I removed teh polycrylic, and now I am stuck deciding which polyurthane to use. I dont have sprayer and what wondering if you thought the rustoleum spray poly could be a good choice. they say they have one that goes on metal as well as wood. do you think that would work?

many thanks

Chris

BrianJewett (author)  crob15 months ago
Yes. If you have clean bare metal, that's what I would use. If you have any rust, I'd put on a coat of penetrol first to neutralize it. Then carefully and lightly do some fine wet sanding to level out any brush marks. when it's clean and dry again, I'd give it several coats with the spray poly. That's what I did with the bathroom countertops 4 years ago. So far, so good.
crob1 BrianJewett5 months ago
Thanks Brian. I will give it shot and see how it works out.
ShandaS6 months ago

Hey, just wanted to add my appreciation to you for taking the time to post this VERY helpful information! I recently started working with metal and, like others, have searched for a solution to keeping the rusty look without letting the thing just rust away. I've seen a lot of mention about Corten metal, but for my local shop it's a custom order and pricey. You saved me!

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BrianJewett (author)  Keegan McClain9 months ago
Hmmm... It looks like a question I got in my e-mail has been removed but it you were still wondering, I'd wipe the panels down with mineral spirits or alcohol to remove any oils ant then either use the Penetrol & polyurethane top coat or since there's no rust on the new panels, you could seal them with a paste wax. This looks like naked steel but still seals the surface to prevent rust.

Thanks for the help Brian. Here a pic of the new Design area at Noble Plastics. The renovation is not done, but the walls in the design studio look and work great!

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I'm working with Keegan on this project. How much area can we expect to cover with 1 gallon of the Penetrol?

Also, can you recommend a matte polyurethane top coat? Does it matter if it is oil-based or water-based?

trishbohr6 months ago

Hi, I bought 90' of antique iron fence panels. They have been stored outside for years and are pretty clean but have surface rust. I love the aged appearance and It sounds like Penetrol might be a good option for me. I don't want the structure to rust away. Do you think Penetrol would work to preserve them and would you apply a sealer to finish them and protect them from the Midwestern winter?

Thanks,

Trish Bohr

Iowa

BrianJewett (author)  trishbohr6 months ago
I don't have any experience with long term weather exposure so I'm not sure. I think the Penetrol is linseed oil based with hardeners. You may be better off without the polyurethane over coat outside so you can just re-coat them periodically without sanding. If you have a really good paint store (not just a hardware store) in your area they might be able to answer this better than I can.

Thanks Brian. I sanded and used Penetrol on a 10' panel today and love the look. I rubbed the Penetrol on with a cloth glove and it covered easily so re-coating wouldn't be a big deal. I appreciate your help!

BrianJewett (author)  trishbohr6 months ago

You probably don't need to sand. Just knock off the loose rust with a steel wire brush, then clean the dust off with a hose and let it dry well. Wire brushing will get into the low spots better and won't change the surface texture.

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