How to Fix a Microwave after Putting Metal in it? (3 Best Solution)

Metals don’t absorb microwave radiation from the microwave oven. Rather the metals reflect the radiation. But when you microwave certain metal structures, it can cause arcing and sometimes create plasma inside the microwave oven. So, in that case, you need to know how to fix a microwave oven after putting metal inside it. 

How to Fix a Microwave after Putting Metal in it

How to Fix a Microwave after Putting Metal in It?

Microwaving metals can cause burn marks and holes in the inner body. If you have burn marks inside the metal cavity, you can fix it with the help of appliance touchup paint. If you have burn holes inside the metal cavity, then you cannot repair it and you have to go for a replacement of the appliance. When the issue is with the waveguide, then you can simply replace the waveguide and use the microwave normally.

Fixing Burn Marks Caused by Metal Arcing Inside a Microwave Oven

A common issue that arises after using metal in a microwave is black marks with slight erosion of the metal cavity. These marks can be found on the cavity where the metal has made contact with it. When a metal touches the metal cavity, arcing might happen and cause these marks at the contact spot. The following procedure will help you to fix these burn marks easily.

Things required:

  • Sandpaper with CAMI 100 or 150 grit
  • Microwave Cavity Touch Paint (as per requirement)
  • Cloth to clean the surface
  • Gloves for safety

Prep Time – 15 minutes

Total time for the fix – 24 hours


  • Turn off the microwave and unplug it. Take the microwave to a well-lit workspace.
  • Check for marks inside the cavity. If they are small, then you can easily get rid of them. 
  • If you have marks outside the metal cavity, like the door mesh or on the entrance of the cavity, then don’t try to fix it by yourself. Take the appliance to a technician.
  • Once you have found all the defects inside the cavity, use sandpaper to smoothen the rough edges and the surface of the affected area. Don’t rub the surface too much because it may damage the metal surface.
  • After smoothening the surface, take the touch paint for the microwave cavity and apply a coat over it. Let it dry for a few minutes.
  • Now apply a second coat slightly thicker and make sure to cover the marks completely.
  • Let it dry for 24 hours and it is better to leave the door open. 
  • After 24 hours, you can start using the microwave oven normally.

Replacing the Waveguide Inside a Microwave Oven

A waveguide is a small plastic or mica sheet that is fixed on the side of your microwave cavity. This is fixed to prevent microwave radiation from entering the magnetron.

When you microwave a metal, there is a possibility that the waveguide is damaged. If there is complete damage, then you need to replace it. If only carbon soot has deposited over it, then you can clean it to avoid getting further arcing.

Things required:

  • Cloth
  • Cleaning solution
  • New Waveguide or a Mica Sheet

Prep time – 10 minutes

Time required for the fix – 20 minutes


  • Locate the waveguide inside your microwave oven cavity
  • Some microwave waveguides can be removed just by sliding them out of the slot. Some models will have a rubber rivet which you have to remove to take the waveguide out. Some may have screws too.
  • After removing the guide, check for any damages. If it didn’t have any damage, simply spray some cleaning solution and wipe the carbon soot deposit thoroughly.
  • If it is damaged and has holes it in, there are two ways to rectify it. Either you can buy a new waveguide from the store or make one using a mica sheet.
  • To make one with a mica sheet, buy a thin mica sheet and cut it to the shape of your waveguide. If it has screws or rubber rivets then make holes in the appropriate areas.
  • Now fix the mica sheet over the area where the previous waveguide was present.
  • You have fixed the microwave oven completely and you can use it normally.

Fixing Electrical and Electronic components of the Microwave Oven

If the microwave is damaged due to the arcing and the circuit components aren’t working, then it is not advisable to fix them on your own. Make sure to take it to a technician and get it fixed. 

When you have left the metal for a long time, it might have created plasma and could have made a defect in the cavity. This can further affect the circuit components and the microwave may not work thereafter. Sometimes, it may turn on but will not heat the food.

In certain cases, the electronic switches and board buttons will not work. So, in such situations, you must take the microwave to a technician and get it fixed. With severe damage, you might have to replace a major component or get a new one.

Do All Metals Cause Arcing When Used in a Microwave Oven?

All metals reflect microwave radiation. However certain structures and forms can cause arcing and might even lead to plasma production. Here are the metal structures and forms you need to avoid in a microwave:

  • Things with sharp metal edges
  • Thin metal sheet
  • Crumbled aluminum foil with sharp edges
  • Metals coming into contact with other metals
  • Metals contacting the metal cavity of the microwave

Only these types of metals will create an arc within the microwave oven and might even create plasma. Even if you keep two grapes in close contact and microwave them, it will create plasma.

You can check out the video from the YouTube channel TKOR (The King of Random) where they experiment with different types of metallic items in a microwave. You can witness that, most of the time, a small arcing doesn’t damage the microwave. 

So, you can put your coffee mug with a metal spoon inside the microwave. But make sure to put it right at the center of the turntable and avoid putting another metal in contact with it. There are other things to avoid putting in a microwave. check them out and prevent your microwave from being damaged.


It is not advisable to microwave metal. But if you had accidentally thrown in a bunch of spoons or aluminum foil, then they might start arcing. If the arcing is for a few seconds then you don’t have to worry. But if too many arcs are created, then you can get marks inside the cavity and you can fix it with the recommended solutions. 

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