There’s Rust Inside My Microwave! Is it Safe to Use?

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Dear Home-Ec 101,
I have a rusty microwave and I’m worried. I know that there has always been some rust inside my microwave door, but recently I noticed it has become a lot of rust. I wiped it, shut the door & reopened it, and saw the rust dust was spreading.

I only use my microwave for reheating the occasional steak or cup of coffee or steaming a package of green beans. Which does, by the way, create a LOT of steam, which may be why it got so rusty in the first place.

Is there a way I can fix my rusty microwave or can I just ignore the rust in my microwave? Is it just no big deal or should it go to the great appliance heap in the sky?

Signed,
Rusty Redhead

P.S. You can see it pretty clearly in the picture.

Rusty microwave door

Great question, let’s break it down into a couple of parts. First, for those who need some background, here’s a quick refresher on how microwaves work. The key thing to remember is that microwaves are an appliance that keeps the microwaves (the ones that cook the food) contained to a specific area. It’s also good to remember that microwaves are not the scariest kind of radiation—it’s not going to make your hair fall out.

Still, it’s best to keep those microwaves in the box where they belong.

IF the rust in a microwave were to reach a point where it compromised the door’s integrity, there would be a potential for the other microwaves to escape. However, even if they did get out, they aren’t going to chase you down the hall, out the door, and down the street. Just don’t stand there with your nose pressed against the glass like a puppy wanting back in the house. I don’t recommend doing that for the record, even with a fully intact, non-rusty microwave. Stuff happens, power surges, exploding pyrex, etc. You like your eyes, don’t you? I do.

The Michigan State University Extension says:

If there are signs of rusting inside the microwave oven, have the oven repaired.

Cosmetic surface rust is not a safety issue, but don’t ignore it either. Rust can and will spread, and what starts as cosmetic will eventually become more invasive if ignored.

Doesn’t this sound a lot like something your dermatologist will tell you?

How to repair a rusty microwave oven

If your microwave’s door or cavity only has surface rust, do the following.

How to Repair a Rusty Microwave

How to Repair a Rusty Microwave

Prep Time: 10 minutes
Active Time: 30 minutes
Additional Time: 3 days
Total Time: 3 days 40 minutes

If a microwave's cavity has cosmetic rust, it can safely be repaired with fine-grained sandpaper and microwave paint

Materials

  • Fine-grained sandpaper
  • Microwave Cavity Paint
  • Painters tape
  • Paper
  • Degreaser
  • Clean rag

Instructions

  1. Unplug the microwave
  2. Move the appliance to a well lit and well-ventilated area
  3. Clean out the cavity of the appliance thoroughly with your rag and degreaser
  4. Use fine-grained sandpaper to remove all surface rust and any flaking or peeling paint.
  5. Tape over any areas that should not be painted. Be sure to cover the vent.
  6. Spray the affected areas in light coats, allowing the paint to become tacky between coats and stop when the bare metal has been fully covered. Do not create a thick coat of paint
  7. Allow the paint to cure fully. This can take up to 3 days in very humid environments

Notes

You MUST allow the paint to fully cure before operating your appliance. It is dangerous to operate your appliance prior to that point.

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Remember you must allow the paint to FULLY CURE before operating your microwave. Paint fumes are highly flammable and operating the microwave before the paint has fully cured is not safe.

how to clean appliances
Click the picture for more tips!

How to prevent rust in a microwave oven.

To prevent rust from reoccurring in your newly painted, rust-free microwave, you could leave the door ajar after cooking or cleaning to allow the moisture a chance to escape.

Another way to prevent rust in your microwave is to wipe down the door and cavity walls of the unit with a dry towel after use.

As a bonus, with this method, you would never have to deal with petrified food build-up. Unfortunately, just knowing how hard it is for some people to cover their food while using the microwave, I can see how most would balk at the idea of ANOTHER extra step, even if it extended the life of their appliance.

In either case, reducing the amount of moisture the walls and door of your microwave are constantly exposed to will significantly reduce the opportunity that rust has to form

TL;DR Is Operating a Rusty Microwave Safe?

A little cosmetic rust in your microwave is not a big deal.

You can safely remove the rust and paint the interior of your microwave following the instructions above. Rust that has created even pinholes is a safety issue and should not be ignored.

Replace microwaves with significant rust damage promptly.

Again, the microwaves that cook your food are not going to hunt you down and give you cancer, but microwaves escaping the appliance are still a safety issue. Do not operate a microwave with significant rust damage.

Regarding the microwave in the submitted picture. I can’t see if that rust has created holes. You will need to look carefully and determine how much damage there is.

A little bit of searching shows that most microwaves do not sell replacement doors as an option. Don’t be too upset if it is time to retire your rusty microwave. You now have the knowledge and the skillset to make your next microwave last much longer.

Good luck!

Submit your questions to helpme@home-ec101.com.

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6 thoughts on “There’s Rust Inside My Microwave! Is it Safe to Use?”

  1. I purchased a new Tower microwave just over a year old and the inside is going very rusty forgot to register for the extra 2 years as most of my microwaves have lasted 8 to 10 years with no problems so not very happy spoke to Tower and told me to send photo of rust inside did this and said they would get back to me in 48 hours this was on the 5 of November sent 3 more emails nothing rang them 3 times rang at 4 30 pm was told waiting time is 2 min waited 30 min nothing then was told to ring between 8 30 am and 6 pm well I did so service not good the 3 year guarantee was on side of box and information telling you to register within 28 days was on the bottom of the box I missed it also right at the back of the instruction book missed that too why was it not under the 3 year guarantee label so you could see it I now and so do you they don’t want you to see it hence did not get 3 years

    Reply
  2. I have the same microwave and same issue and noticed also recently it has seemed to spread like crazy – overnight! I am worried that this is a health hazard. I totally understand the importance of leaving the door ajar after use for steam to escape and wiping dry after use……now! I have had multiple microwaves in the past and this is the first this has happened.

    Reply
  3. I have the same microwave. I have also seen two other models rust in my area. I live on the West Coast. Since this never happened when I lived in the humid Midwest or the South, my theory is that the salt in the air does it. My computer parts also rust for no reason when stored away.

    I have rubbed a bit of castor oil onto a tiny spot that has started on my latest microwave. It’s thick and it gets gummy so it should prevent further spread. I would replace the microwave if there is extensive damage beyond that.

    Leave the door open for a while after cooking.

    Reply

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