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Can You Microwave Aluminum?

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From takeout containers to foil, aluminum is conveniently used for storing, cooking, and reheating food. Aluminum is an excellent conductor of heat, therefore heat generated inside a microwave transfers to the food to achieve even heating. 

But the safety issue is still questionable. 

Can you microwave aluminum? Yes, you can microwave aluminum. However, there are specific ways to use aluminum foil or trays, and not all aluminum is safe to microwave.

Ensure to read the heating instructions provided by the manufacturer before using even a small amount of aluminum in the microwave.

Consider using smooth and brand new foil to prevent sparking, avoid making any sharp edges, and make sure that the aluminum does not touch the microwave oven walls. 

Microwave heat does not pass through the metal, but is easily absorbed by food. Therefore, it is best to not cover the food completely when using aluminum and keep a minimum of ¼ open.

Even when looking at microwave safe symbols, microwaving aluminum can become intimidating. In this article, we are going to investigate the relationship between aluminum and microwave to answer all frequently asked questions about the safety and concerns.

Can I put aluminum foil in to microwave?

Yes, you can put aluminum foil in the microwave. However, it is only safe when you do it right, and can quickly turn into a nightmare if done incorrectly.

The aluminum sheet foil tend to block microwaves from the food, which helps to protect from burning. As a result, it is recommended to not cover more than 75% of the food.

Always read the microwave owner’s manual regarding the capability to nuke aluminum. Additionally, consult the container or foil to see if it is microwave safe or not by following instructions on the bottom of the packaging. 

  • The shiny and dull side does not make big difference when used in the microwave. 
  • Do not cut foil into strips because that will concentrate the microwaves. 
  • Stick with foil that is wider and longer than 1 square inch.
  • Avoid using wrinkled foil because it can easily cause sparks. 
  • Use new smooth foil and if needed mold and shape without sharp edges, be sure to round all corners
  • Do not use aluminum foil as lid to cover the dish to microwave. It will make the top of the food dry out quickly before the bottom layer starts to heat. 
  • Place loose foil wrapped food in the center and several inches away from the inside wall of the appliance. 

Even though following the restrict guidelines, if you see sparks while using aluminum foil, stop heating and transfer your food into a microwave-safe container to continue the process.

Can you microwave aluminum tray?

Yes, you can microwave aluminum trays. Actually, it is safe to put them in the microwave, but ensure that the tray does not touch the inside of the microwave and do not cover with a lid. 

Aluminum trays allow heat to distribute homogeneously to improve cooking, storing, keep food warm, and baking dishes to maintain the heat flow. In addition, there is no harm of cracking, melting, or burning the cookware.

Because this type of metal container cannot be penetrated by microwave energy, a depth of only 3 inches is recommended for the food to be absorbed and cooked or reheated all the way through.

In some point, aluminum is a great tool to prevent food from overheating when making sauces or condiments. 

Check the microwave-safe symbol under the tray and only use shallow aluminum trays that are no deeper than 3 inches.

Do not cover with lid and avoid getting too close to the sides of microwave because this will cause a spark and may ignite the appliance.

Unless heating instruction are provided, increase the cooking time by 10% and avoid using damaged or bent foil trays. 

What happens when you microwave aluminum?

Microwaves are generate electromagnetic waves that impact water molecules through friction that results in heat. However, these waves bounce off metal making it challenging to heat up food in metal containers.

When aluminum is microwaved, the metal acts as a reflective that bounces most of the energy off the surface. In addition, the microwave walls act as a conductor that can create spark instead of penetrating to the food. 

Metal with sharp edges or jagged pieces overheat and result in quick reaction that collects electricity in the form of ionization. The effect is called electrical arcing where the dangerous sparks will begin.

Why does aluminum spark in the microwave?

Without being cautious, aluminum may create sparks while microwaving. 

High voltage builds up that exceeds the voltage of air, which leads to sparking. Sparks also happen when the metal pieces are very thin such as foil or a stainless steel fork. 

The microwave relies on a magnetron that has a vacuum tube going through a magnetic field. This element spins electrons around and produces electromagnetic waves with a frequency of 2.5 gigahertz. 

When microwaves interact with aluminum or any metallic material, the electrons in the material’s surface get moved around and look for edges. As a result, the charges gathers together and result in a high concentration of voltage. 

The ionized particles absorb microwaves even more than water and create sparks. When the microwave begins ionizing more molecules, the spark grows bigger and ultimately results in fire.

Aluminum foil in microwave

Microwaving Aluminum: Conclusion

From roasting to pie plates, soups, and stews, there are many ways aluminum is used to shield parts of food to allow them to cook evenly without burning. It is such as useful kitchen tool, but use it carefully to prevent from spark and fire hazard when microwaving.

Whether using aluminum foil or tray, eliminate covering the food more than 75% and dishes no deeper than 3 inches. Make sure to use only unwrinkled foil and smooth side.

If the aluminum has damage, sharp edges or bent corners, simply throw it away and do not use in the microwave. 

When microwaving food with aluminum, consider heating small amount so the container does not touch the inside walls of appliance. 

If you are still uncertain, look for microwave safe symbol and microwave’s manufacturer guidelines regarding aluminum for any tips and warnings. 

Even when following these strict regulations, if you happen to experience a spark, cease microwaving immediately to prevent a potential hazard. Simply use non-metal items to warm up your food such as paper towel or plastic wrap to cover ceramic or glass containers.