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The Best Way to Remove Rust Caused by Cat Urine

I like to tackle home projects myself and write about tips for other enthusiastic DIYers.

The rusted air grill before . . . .

The rusted air grill before . . . .

How to Remove Urine From Metal

Have you ever known a cat to spray, aka urinate, on metal items such as the vents on the bottom of some refrigerators, or in my case, on my air return (a large metal register for my furnace)? I’m not the only one who has come across this issue, as evident by the number of people complaining online and trying to find a solution to the problem. How do you get rid of the rust caused by cat urine? Is it better to paint the vent or totally replace it? And will the cat (or cats) go back to mark it again?

In my case, I was able to repair mine (although replacing it may have been easier), and neither of my male cats has been back to leave his mark. And, yes, male cats do still spray their stuff even after they have been neutered.

So my plan was to go the cheap route by getting rid of the rust and painting myself. Easier said than done, I will tell you. I researched how to accomplish this feat, and, after some trial and error, was successful. Perhaps you can learn from my mishaps and have a much easier time should you ever have to repair rusted metal caused by cat urine.

Final Product: Repainted register wall

Final Product: Repainted register wall

Getting Rid of Rust Caused by Cat Urine

  1. Sand. First, I sanded down the rough rusted parts with sandpaper. Sanding down the vents was a time-consuming job, and I probably could have spent more time to get them smoother, but I sanded until I could sand no more. I used my leaf blower to blow as much dust as I could off the grill.
  2. Clean. Then I wiped down the vents with water to make sure they were clean and dust-free.
  3. Paint. Next, I was ready to paint. Since my insert had been there for many decades, most likely, it was way too difficult for me to unscrew it from the wall. Because of this, I decided to paint the thing while it was still in the wall. I spread newspaper underneath on the carpet, on the adjoining walls, as well as inside in front of the screen that looked underneath the house.

How to Paint the Register

When painting, it's best to do light coats, allowing them to dry before adding another coat. One thing I learned during this process was to make sure your paint isn’t too old. I couldn’t understand why I couldn’t cover up the rust after several coats. I about threw up my hands and gave in to buying a new insert. Before doing that, however, I decided to give it one last shot with some new paint. That did the trick!

I purchased paint that claims to stop rust and cover up everything. With the first light coat, the rust started to disappear. After a few coats, the vents looked brand new. I was quite pleased with myself for doing my own little DIY job.

I saved at least some money by doing it myself, even if I didn't save time. However, I do think that with the right tools from the start, especially new paint, the job would have taken only an hour or so.

Estimated Cost of This DIY Project


Fine to medium sandpaper

.97 (one sheet at

Rustoleum (or other) spray paint


Total Cost:

approximately $5.30

Summary of Steps

  • Remove majority of rust by smoothing with sandpaper.
  • Remove dust with blower if desired.
  • Wipe down vents with damp cloth.
  • Spread newspapers on floor, walls, and inside air return.
  • Spray paint in several light layers, allowing them to dry between layers.

Did the Cats Return to the Scene of the Crime?

I have cats. I deal with cat urine. This spraying on metal was new to me, but I figured out how to handle the problem and am very pleased with the results. Have the boys returned to the spot to do their business there again? I am thrilled to say that no, they haven't.

This makes me think that the odor was also removed and the problem is solved. My fingers are still crossed. I hope this has helped other cat-loving, do-it-yourselfers who might run into this problem.

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Read More From Dengarden

Get the right type of paint! This rustoleum spray paint has paint plus primer all-in-one.

Get the right type of paint! This rustoleum spray paint has paint plus primer all-in-one.

Cat Urine on Metal Poll


Sharon Sleszynski on November 01, 2017:

Yes, I have an animal rescue, & cats urinated on bottom of refrigerator door. I have a wonderful auto body repair tech. So I asked him to use the electrostatic method to paint the door. He did a wonderful job, & now has a new service to offer his clients! ( he didn't think it would work, it did!) the cost was nominal, ( $75.00) compared to cost of new refrigerator!

Victoria Lynn (author) from Arkansas, USA on August 19, 2013:

Glimmer Twin Fan--I guess replacing the register is an easier way to do it, but this might save a few bucks. Thanks for the comments!

Claudia Mitchell on August 18, 2013:

I had a cat many years ago and this was a huge problem. Wish I had this then. I would just replace the floor registers every few years when it got really bad. It was only on one register too. Useful hub, pinned too.

Victoria Lynn (author) from Arkansas, USA on July 31, 2013:

toknowinfo--Glad the piece was inspiring. Those are very nice comments! Thanks!

toknowinfo on July 29, 2013:

You have a good mix of creativity and patience and of course a love of pets. It looks like you created a like new piece. It is very inspiring. Thanks for all your great tips. I look forward to reading more of your wisdoms.

Victoria Lynn (author) from Arkansas, USA on July 14, 2013:

random--Hopefully, it won't happen to you, but, if it does, it's good to know you can repair the damage yourself without toooooo much trouble. :-) Thanks for the comments!

Victoria Lynn (author) from Arkansas, USA on July 13, 2013:

Aw, MizB, our cats sure keep us hoppin', don't they? I would be afraid to cover the concrete if they have peed on it. Plus, isn't it easy to clean? Cat are so funny and finicky! I loved your comments. Thanks so much. And for the vote!

Victoria Lynn (author) from Arkansas, USA on July 12, 2013:

Kathryn--You're right in that it's natural for them. We just have to put up with them and love them anyway. LOL. Thanks for the comments!

Rose Clearfield from Milwaukee, Wisconsin on July 11, 2013:

Thankfully this has not ever happened to me (though I shouldn't speak too soon), but it's great to have this resource on hand in case it ever does!

Doris James MizBejabbers from Beautiful South on July 11, 2013:

Sounds like you did a good job on your register. If you got off all the old rust and sanded down to the bare metal, the Rustoleum paint should do the trick. Luckily I haven’t had to deal with cats spraying registers because ours are up high. One of my late cats, Seaball, would back up to a bush outside, like my prize rose bush, and spray. Tas now just pees in the floor whenever he is upset or thinks he needs to go to the vet for cystitis. A trip to the vet (whether he needs it or not) usually stops that for several months. We have concrete floors, and I’m thinking about covering them but I wonder if tile would cover up the scent that has seeped into the concrete. My new girl, Cici, is every bit a lady and doesn’t like it when Tas uses her box. Voted you up++

Kathryn from Windsor, Connecticut on July 10, 2013:

This would have come in handy a few years ago! It is awful to have to deal with rust from naughty little critters. Although I suppose they can't be blamed too much for doing what is natural for them to do, but it is frustrating!

Thanks for sharing this with us, and have a good night.

~ Kathryn

Victoria Lynn (author) from Arkansas, USA on July 10, 2013:

FlourishAnyway--So the girls spray, too? Wow. Mine might go outside the litter box, but I haven't seen them spray. You're right! I need to spice hings up with pics of my bad boys! Great idea!

FlourishAnyway from USA on July 10, 2013:

Helpful tutorial for cat lovers. Unfortunately, it's my beloved female kitty who does pesky things like this. When feeling miffed by another cat in the house, she backs straight up to a door, wall or yes, the metal register and sprays. Prior to her, I didn't even know they could do that. Well written and illustrated with excellent how-to photos. You should consider inserting pretty photos of the offenders. Those bad boys Oliver and Simon deserve some positive press too, huh? Voted up and more.

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