Letter 30522

Clear coat finish over rusted metal

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I am a PM and have project with a situation and was looking for any information I could find on clear coat. I have a 20 ga cold rolled steel that has been cleaned (w/soap & water) and then we applied a solution of water/acid to speed up the rusting process. We then applied a semi-gloss lacquer (3 coats / interior application) using a "Deft" product. Now that the metal is in place some of the finish is coming off and taking the rust with it (rusted look was the desire) Is there a product that we can put over the lacquer that will stand up to abuse (prefer clear coat) or do we have to take off the lacquer before we can put anything else on it.

Thank you for any assistance you can offer.

Ed Smith
sheet metal subcontractor - Blue Springs, Missouri

I have the same interest as Ed in clear coating over a rusted surface. In my case it is for steel sculpture, as I do fairly large pieces for indoor and outdoor use. Many times I want to keep the rusty look. Any suggestions?

Thanks,

Ken MacDonald
- N. Kingstown, Rhode Island

Like Ken and Ed I am interested in an exterior clear coat that will work on rusted metal. We are expanding our signage to include etched and distressed metals and need a durable clear for exterior use.

Thanks,

Steve Halmhofer, shop manager
- REDDING, California

I think that you can use proprietary polyurethane paint or spray. Some of them contains rust inhibitors (Krylon spray). Good luck!

Goran Budija
- Zagreb , Croatia

I have been using the same approach to accelerate rust and have been experiencing the rust peal you describe. It is my belief that the acid causes the rust to happen too fast. I suggest you experiment a little with vinegar. That seems to work fairly well and quickly. Also be aware that the texture is different than with the acid.

Allan Polinsky
- Lodi, California

I am interested in the how much vinegar to mix with water to give me a mottled rusted finish on steel and then clear coat.

John K. Martin
- Rockford, Illinois

Duh, why coat it with anything? If you want a rusty finish, just leave it alone and it will take care of itself.

Bob Weber
- Shawnee, Oklahoma

If any one knows of a clear surface film finish that could be used over rusted metal I'd really like some feed back on this. I know that you could use Linseed Oil [link is to product info at Rockler] and maintain it every year. the project that I'm working on is Rusted Iron Gates and handrails and its all exposed outside to the weather. Thanks,

Jim Popp
custom painting - Post Falls, Idaho

I am trying to find a way to clear coat artificial patina without creating bubbles in the clear coat. I am guessing that the chemicals are gassing beneath the surface. Is there a way to neutralize the acids and prevent the gassing?

Olivier M. Odom
metal work - Asheville, North Carolina

In Response to neutralizing.... baking soda will neutralize acid. Wipe the surface with water/baking soda mix and drying it fully, quickly. it will stop the patina process.

Kristina Kozak
- Brooklyn, New York

I've been through all the threads, and I didn't manage to find any definitive answers on a clearcoat finish on rusted steel.

I have an old steel welding bench from the 60's, it's rusted to a perfectly natural (almost uniform) rust pattern, and I am using it as a counter in my kitchen. I want to protect the rusted finish with a clearcoat that can withstand plates and dishes and such abrasive surfaces & wet/oily substances.

Is there a product out there that I can use to simply seal the surface the way it is now thus clearcoating it?

Thanks for your help, and for all the info in the threads - very useful indeed

Cheers
Rich

Richard Belliveau
- Fernie, BC, Canada

Hi, Richard. I suspect the reason you couldn't find a clear answer is that there isn't one :-(
It's said that a chain is only as strong as its weakest link. Here we have a link of steel (your welding bench); then a link of loose, powdery, non-adherent rust. Then a link of clear coat. And people report that as stress is put on the clear coat, the clear coat pulls off "taking rust with it".

I suspect that if the rust is quite thin, such that the clearcoat can "wet" it all the way through to where the clear coat can actually grab sound steel, you may get marginally acceptable adhesion.

Ted Mooney, P.E.  finishing.com Brick, New Jersey

I have the same problem as the other people. Have a rebar viewing fence with stucco wall at the bottom. It's supposed to be rusty. But the clear coating the fence people used is washing off allowing it to further rust on the stucco, my flagstone patio and the front sidewalk. Need something to seal it with. Hope you can help. Deborah

Deborah Dillon
- Gold Canyon , Arizona

Automotive clearcoat. Seals the rust without inhibiting the appearance, and the thicker you lay it on, the more protected you are. If it gets severely scratched, just buff with a little clear coat polish and a buffing cloth.

Rob Lawson
- St. Louis, Missouri

Wow, this is great. I have a set of 1950's metal garden chairs and had them sand blasted and let them rust to a wonderful color. You just can't sit on them without getting orange stripes on your clothes. Will try the automotive clear coat.

Question? Multiple thin coats, or one heavy coat? Should I wipe them down first and if so, use what product?

Thanks for the great information.

Rose Middleton
interior designer - Kansas City, Missouri

Hi, Rose. A couple of thin coats is probably best, but you must wire brush any loose rust off first. A chain is as strong as it's weakest link. If the rust doesn't adhere to the substrate, it does not good to have the clearcoat adhere to the rust -- it will just come off together.

Regards,   opt  

Ted Mooney finishing.com Brick, New Jersey

For my restaurant in Portland, we formed sheet steel panels to fit our back bar, laid them in the parking lot and sprayed them with muriatic acid (diluted a lot) and salt water and let the rain finish the job. When finished it looked like marble and burled wood--nobody guessed it was rusted steel.

We burnished it with fine steel wool to remove any powdered rust, leaving a smooth and intact finish and polyurethaned everything. We put a few coats on, as I recall.

It was inside and not exposed, but in the 8 years I had the restaurant (before I sold it) it showed no signs of additional corrosion or breakdown of the poly finish.

Looking at clear powder coated finish for my next project.

Michael

Michael Teahan
- Glendale, CA USA