Microwaves are our best kitchen companion. They come in handy when we want to cook or heat up a meal/drink. However, there are myths on what you should or not put in a microwave.
We have at one time received a warning against putting aluminum foil in the microwave. The main result, as told or seen in viral videos, is fire. But, how valid is the reasoning?
Can you put aluminum foil in the microwave? You cannot put aluminum foil in the microwave. Placing aluminum foil in the microwave may lead to arc/sparks, smoke, and flames. Aluminum foil is made from pure metal. The thin metal gets overwhelmed by the electromagnetic radio waves being produced. The aluminum foil heats up and produces sparks that may lead to flames in your microwave.
A microwave oven uses electromagnetic radio waves (microwaves) to heat up or cook food.
Microwaves have a frequency length of about 2.5 gigahertz. Fats, sugars, and water easily absorb it. When the waves are absorbed, they get converted into atomic motion, which is heat.
The conductive property of the fats, sugars, and water carries the heat to the center. This is the process that causes the food/drink to heat up in the microwave.
The frequency passes through plastics, paper, glass, and ceramics. These are safe materials for microwave containers.
According to FDA, aluminum foil should not be used in a microwave oven. Microwaves get bounced off the foil, which may cause unevenly cooked food or damage to the oven.
What Else Can’t You Place In A Microwave?
- Metals
Thick metals bounce back the waves when used to warm food in a microwave oven. It means that food will not heat up.
Thin metals like aluminum foil get overwhelmed by microwaves. The metal heats up instead of the food leading to sparks and possible flames in the microwave.
- Paper bags and cardboards
These materials easily absorb sparks and may catch fire if put in a microwave. More so if there is an aluminum foil in the microwave oven.
Cardboard may be used to warm food in a microwave but only for a short time. Prolonged use plus high temperature may result in flames.
- Kitchen Sponges
They are flammable when dry and may cause fire damage to your microwave oven or even house.
- Any plastics without a “microwave safe” label
They melt under microwave pressure and may explode, damaging your appliance.
- Clothes
- Styrofoam
What If I Put Aluminum Foil In The Microwave?
The walls of a microwave oven are made up of metal that bounces the microwaves back and forth. Food absorbs the waves, and the food heats up.
Aluminum foil being thin metal does not reflect the waves. The waves which contain electric currents concentrate in the foil leading to overheating. Sparking may be experienced.
Sometimes you have to fold the aluminum foil, and it forms corners, bends, edges, or sharp wrinkles. These characteristics concentrate the electromagnetic fields in one area.
The concentration of the fields leads to overheating. Sparks known as electrical arcing may occur in the microwave as a result. Fire flames may appear shortly after.
Electrical arcing in a microwave oven is a result of ionization. The sharp edges of the aluminum foil gather electricity fields. The fields are strong enough to draw electrons from air molecules.
Putting a small aluminum foil in the microwave oven may not lead to an explosion. But, it is always good to remember that it only takes a tiny spark to start a fire.
If you have to use aluminum foil in a microwave under any circumstance, keep a close eye on it. Turn your microwave oven off when you notice a spark and unplug it from the power source.
If you still aren’t convinced of the potential ramifications of sticking aluminum foil in a microwave, check out this video from the SciShow.
Best Aluminum Foil Alternatives To Use In A Microwave
Glass
Not all types of glass are safe for use in a microwave. Ordinary glass is too thin to use in a microwave. Use Borosilicate glass pans. They are safe for heating food in the microwave. One highly recommended choice can be found here!
Silicone
Silicone is an excellent material for use in microwaves. Food-grade silicone pans are indestructible hence safe for microwave use. For those interested there exists coverings that can be used for microwaves without fear of melting, releasing chemicals, or causing any sparks. EZY ACTIVE that is available on Amazon offers a fantastic choice for those interested that use the microwave for their food heating needs. Take a quick look at the listing, here!
Ceramics
Best ceramic containers to use include lasagna pans, tagines, and quiche pans.
Why Does Aluminum Foil Burn In The Microwave But Not In An Oven?
To answer the question, we need to analyze the heating techniques of each appliance.
How Conventional Ovens Work
A conventional oven is a household appliance that you use for baking/broiling/grilling. It is enclosed with metallic components at the bottom and the top.
Electric currents flow through the metallic components heating the element. The internal space of the oven heats up. In turn, the food in the oven heats up or cooks.
Conventional ovens have a preinstalled thermostat that measures the temperature. It adjusts the electric currents through the element.
What Is The Difference Between Microwaves And Ovens?
Microwaves use electromagnetic waves which generate frictions through the emitted vibration. The friction causes heat, and your food begins to warm up from inside out.
Ovens generate heat into the entire space when the coils heat up and warm the air. The food directly absorbs the heat from outside. This occurs until the food temperature matches the air temperature.
Why does aluminum foil burn in a microwave but not in the oven? Aluminum foil absorbs the electromagnetic waves generated in a microwave leading to sparks. Aluminum foil absorbs the evenly heated air from the oven and transfers the heat to the food.
As mentioned, the thin metal does not reflect the electromagnetic waves. The waves concentrate on the foil, which overheats, leading to arcing. Flames may occur as a result.
A conventional oven supports all types of metals with no risk at hand. The entire interior of the oven is evenly heated up. The foil absorbs the heat, not waves, and transfers it to the food.
Would Aluminum Foil Destroy A Microwave Oven?
Aluminum foil will destroy your microwave through possible arcing, smoke, and flames. Observe precautions to avoid damaging your microwave when using aluminum foil.
Safety Tips For Using Aluminum Foil In A Microwave: USDA Rules
- Use new and smooth foil only. Crisped foil may cause arcing, smokes, or possible flames.
- Cover no more than 1/4 of the food with foil.
- Shape the foil smoothly to the food, so no edges stick out. Edges may saturate currents which may cause sparks.
- Either side of the foil aluminum foil is safe to use. It makes no difference which side of foil (shiny or dull) is facing out.
- Do not place the foil closer than one inch from the oven walls. Placing the aluminum foil close to the wall increases the chances of arcing.
- If the microwave oven has metal shelves or turntable, avoid using aluminum foil or metal pans. If you use foil for shielding food, don’t let it touch the shelves or the turntable.
- Remove the aluminum foil from the microwave oven when you notice any spark. Transfer the food from the foil shielding or container into a microwave-safe container.
How Long Can Aluminum Foil Be In The Oven?
You can put aluminum foil in an oven for as long as the recipe requires. It is safe to use in a conventional oven compared to a microwave.
However, note that aluminum foil may melt when exposed to very high temperatures. This may lead to permanent damage to your oven.
Aluminum foil melts at 660 degrees Celsius at standard pressure. A regular oven temperature ranges between 300-450 degrees.
As indicated above, aluminum foil may not melt in an oven.
But, placing aluminum foil, especially at the top of the oven, exposes the oven to more heat. Letting the aluminum foil sit in the oven after the food cooks pose more melting risk.
Avoid placing aluminum foil at the bottom of the oven to catch spills. The aluminum foil may reflect heat, causing damage to the oven’s heating element.
Using aluminum foil for long may increase the risk of aluminum concentration in food. A 2006 study showed that meat wrapped in the foil had a 375% increase in aluminum concentration.
The study suggests that food cooked in aluminum foil leads to increased health risks. It adds other aluminum sources to your body.
What Happens When You Heat Aluminum Foil?
The medium used to heat aluminum foil plays a role in determining the consequences. While aluminum foil may overheat under high temperatures, it is less likely to catch fire.
Heating aluminum foil below 660 degrees poses zero risks of catching fire. The molecular structure of the foil is tightly packed. Only very high temperatures will cause it to burn.
Here is a list of what may happen when you heat aluminum foil on different heat mediums;
- Aluminum Foil Cannot Burn Over A Stove.
Stoves, whether electric or gas, will not burn aluminum foil. On average, they reach a temperature of about 190 degrees Celsius.
- Aluminum Foil Can Burn In Microwave
Unlike a regular stove or oven, microwaves use electromagnetic currents to warm food. Aluminum foil absorbs the currents and saturates them. The foil overheats, leading to sparks.
- Aluminum Foil Can Cause Damage On Gas Cook Tops
Avoid placing aluminum foil on gas cooktops when cooking. The foil lining traps heat from the top surface of the cooktop. Overheating occurs, which may cause a fire hazard.
Besides overheating, you may experience carbon monoxide gas poisoning in your house. This is because the foil blocks airflow through the oven.
- Heated Aluminum Foil May Cause Leaching To The Food We Eat
Cooking with aluminum foil is common but not advisable. When the foil is heated at high temperatures, leaching occurs. This leads to food contamination.
Aluminum foil, when used in cooking, allows the metal to enter your body. It is not safe for cooking, especially for acidic foods such as vegetables.
Is It Safe To Eat Something That Was Microwaved With Foil?
You may eat food that has been microwaved with foil, especially if it comes in a foil container. Follow the instructions on the package before placing the food in a microwave.
Take off the lid from the foil container to allow the radio waves to reach the food. The microwaves will zigzag around the microwave with the foil lid on, and the appliance may blow up.
A 2014 study shows that exposure to aluminum increases the risk of Alzheimer’s disease. Using aluminum foil to cook increases the chances of aluminum leaching into the food.
3 Things That Affect Aluminum Leaching To Food From Aluminum Foil
- The Temperature Used In Cooking The Food
Very high temperatures increase the chances of aluminum leaching, which contaminates your food.
- The Type Of Food Cooked/Heated Up In The Aluminum Foil
Acidic foods such as tomatoes, kales, most vegetables increase the likelihood of leaching.
- The Ingredients Used In The Microwaved Food
Salt and spices increase the chance of aluminum leaching into your food.
Avoid foils when you have underlying health conditions caused by exposure to aluminum. Use alternatives to aluminum foil or tin foil which are microwave-safe.
How To Test If A Container Is Microwave-Safe
Check for a ‘microwave safe’ label on the container. Some have a symbol of a microwave with wavy lines. If you notice a number 5, the container is made from polypropylene. It is safe.
If the container has no label, use the following steps to check for safety;
- Place the empty container under test in the microwave.
- Place another container with one cup of cold water in the microwave.
- Heat on high for a minute
- Test the temperature of the empty container
- If the empty container is cool, it is microwave safe.
- If it is slightly warm, only use this container for reheating foods and drinks.
- If the container is hot, it is not microwave-safe.
A Data Table Analyzing Some of the Frequent Ways Food Is Covered in a Microwave:
| Best way to cover food in a microwave | Percentage of total results |
| The suggested way to cover your foods in a microwave is with Special Microwave Friendly Covers. | 31.25% |
| Ceramic Plates are a popular alternative used to cover food and prevent a mess in a microwave. | 25% |
| Glass is a very safe material to use in microwaves, so using something like a Glass Plate or Bowl is perfectly safe for microwaves. | 18.75% |
| A quick and easy cover you can use in the microwave is slightly Wet Cloth Towels. | 12.5% |
| Lightly dampened Paper Towels can be very effective as covers for your food in a microwave, this choice is less popular but just as safe. | 6.25% |
| Using Parchment/Wax Paper to cover your food is a less common choice, but can still be used if necessary. | 6.25% |
Final Thoughts
Avoid using aluminum foil in a microwave as much as possible to avoid damage to the appliance. Use microwave-safe items such as ceramic and glass. Do not risk putting any type of metal in the microwave, as it will spark and heat up.
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