Why do you need mica in the microwave and what to do if it burns out?

When a microwave oven starts to spark when turned on, most of us rush to send it in for repair. However, quite often the cause of the breakdown is not so serious and you can fix it yourself. This is the case when the microwave mica burned out. What is it, what is a mica plate for and how to replace it at home?

Why is there a mica plate in the microwave?

In order for our microwave oven to produce microwaves, it has a microwave generator inside - a magnetron. Its waves enter the working chamber of the furnace through a special waveguide. It is its exit that is closed by mica. At the same time, it does not conduct electric current, since it is a dielectric, but transmits any radio waves.

What functions does the mica plate perform?

• Protects the microwave generator from high temperatures during heating or cooking.
• Distributes microwaves evenly inside the chamber.
• Protects the magnetron from aroma molecules, steam particles, fat, food, which inevitably splash throughout the working chamber when using a microwave oven.

This is why the protective mica plate must always be kept clean. After all, moisture particles deform mica and lead to its rapid oxidation. And food debris or fat, falling on the protective mica surface, begins to burn under the influence of radiation from a microwave generator.Then the mica itself burns out, and through these small “gaps” the radiation enters directly into the furnace chamber, leading to a change in the current distribution pattern and, accordingly, to breakdowns. This is where sparks and crackles occur.

To avoid such problems, use a special plastic lid when heating or cooking food, which prevents food particles from splashing.

About the causes of burnout

In addition to the above reasons for the failure of the mica screen, there are also less obvious ones. But all of them sooner or later lead to the need to replace mica in the microwave oven.

• Utensils containing metal or crystal can disrupt the electrical current circuit in the oven and cause sparking “with all that it entails.” Moreover, it does not have to be a completely crystal vase or a metal pan. It is enough, for example, for a spoon accidentally forgotten in a plate, inlay or gilding along the edge of the plate, or a metallized design on a mug. What does crystal have to do with it? Firstly, it cannot withstand microwave loads due to its uneven thickness and can break into pieces right in the oven, damaging our protective screen at the same time. Secondly, crystal almost always contains lead and even silver. That is, they are also metals.
• Even if the dishes are intended for microwave ovens, but their diameter is larger than the plate of a particular microwave oven, during rotation it will cling to the edges of the enamel walls and mica plate, gradually damaging them. That is, sooner or later, with this approach, you will have to not only change the mica, but also paint the inside of the oven.
• The same can happen if the dishes are tall. It is less stable when rotating, so it can “fidget”.
• If the microwave is not installed clearly horizontally, but at an angle (even a very small one, sometimes imperceptible to the eye), when heated, any dishes will “move”, clinging to the enamel.

What to do if the mica plate burns in the microwave?

So, if you hear crackling noises, see sparks or even electric arcs when you turn on the microwave, most likely the mica plate has burned out. The first thing you need to do is turn off the stove and take care of purchasing a new lining. Also for work you will need sandpaper, a stationery or similar knife and special enamel for damaged areas of microwave ovens.

We are not in a hurry to call a specialist - it is quite possible to replace the lining at home yourself.

When purchasing mica, ask the seller for all quality and safety certificates to be sure that you will not harm your health.

It is also necessary to change the plate if an overly clean housewife, while scrubbing the stove to a shine, tore off the protective layer from the mica screen (as a result, the plate becomes deformed and fails), if traces of soot are visible on the surface of the plate (even if there are no holes, soon they will appear). Well, if the holes are more than 5 mm in diameter, we replace them immediately!

How to replace mica with your own hands?

First, disconnect the oven from the power supply. After that, follow this diagram:

1. Remove the damaged cover, depending on how it is attached: with self-tapping screws or plastic latches.
2. Rinse the damaged plate thoroughly to remove any remaining contaminants (otherwise, when cutting, they will end up on the new one, which can cause it to quickly break).
3. Now attach the removed overlay to the new plate and cut out the shape according to this “pattern”.Use a wallpaper, stationery or shoe knife for cutting - their blades are thin and sharp enough for such work.
4. Pierce holes for fastening using an awl or punch with a drill of a suitable diameter.
5. Sand the edges of the resulting workpiece with sandpaper to eliminate any unevenness.
6. Now the new part needs to be washed and dried to remove any remaining dust that has settled during the cutting process.
7. While it's drying, completely degrease the inside of the microwave. Particular care should be taken in the area where the protective mica screen is located.
8. Remove the magnetron (before doing this, briefly short-circuit it and the capacitor to remove residual charge), and inspect it. If not only the cover, but also the protective cap of the microwave generator has burned out, replace it too.
9. If, when the mica plate burns, holes have formed under it, sand them with sandpaper and paint the damaged enamel.
10. When all parts are dry, install a new trim. Installing it will not be difficult, since the location of the old one is clearly marked. This is either a special pocket fastened with a screw in one corner, or metal “tongues” on the body according to the size of the record. In the second case, you will have to bend it slightly to get it into place.

When all the work is completed, you need to make sure that everything is done correctly and the device functions again as before. To do this, the oven must be turned on, having first placed some moisture-containing product inside (at least a bowl of water).

Do not use scissors to cut a new plate. Mica is a material that has the appearance of compacted fine chips. Therefore, it is first applied to a thin but durable base. Scissors will simply crumble its edges, and the workpiece will have to be thrown away.

What can replace mica in the microwave?

If for some reason a new mica plate is not at hand (it was not possible to purchase it or there is no time for it), you can replace it with another suitable material. Which one? Today, even in professional workshops, heat-resistant food-grade plastic is often used instead of mica. It is safe for human health, has qualities similar to mica, but is much stronger, which means it will last longer. In addition, food-grade plastic is lighter and more convenient to use.

But still, experienced repairmen advise not to split hairs, but to purchase mica specially designed for this purpose. Because “native” is always better and more reliable.

Mica in the microwave is a necessary element. Without it, it will not work (at least safely), so under no circumstances should you turn on the oven if the mica screen is damaged, and especially if it has already been removed for replacement. Accordingly, it is important to take care of the fragile but necessary protection. The tips above will help with this. This means that the mica overlay will not have to be replaced soon.