Can Glass Go in the Microwave?

Can Glass Go in the Microwave? Is it Microwave Safe?

Ian Mutuli
Updated on

Today, almost everyone has a microwave oven in their home because it is so useful for heating or cooking food. It's simple and quick to do. Of course, plastic and metal containers are ineligible for use in most microwaves, but what about glass? So, can glass go in the microwave?

Is it Safe to Microwave Glass?

Glass dishes are often used in microwave ovens because they are heat resistant and don't produce dangerous chemicals; hence they do not react with the food they are heating. So, yes, you can microwave glass, and doing so is relatively safe and healthful as well. However, not all glass is used in microwaves.

Is There a Way to Make All Glass Microwave-safe?

Microwave-safe glass does not leach chemicals into the food like plastic when cooked in the microwave. However, due to the extreme temperature changes, some glass may crack or shatter while moving in and out of the microwave.

Of course, certain glasses are microwave-safe and heat resistant. These are labeled with a logo stamped on the bottom of the glass dish. A microwave-safe symbol with squiggly lines appears on the label or logo. However, just because a glass dish does not have a certified safe mark printed on it does not guarantee that it will break when placed in the microwave oven.

Using non-microwavable glass in the microwave may shatter because of the high-temperature changes when removed from the microwave and allowed to cool. Microwave-unsafe glass bowls can shatter because tiny air bubbles are trapped in the glass during manufacture, and these air bubbles expand when the glass is heated in the microwave oven. The glass cookware will shatter if the air in the hollow space (bubble) expands to a certain extent.

Also, keep an eye out for glass trimmed with metal, as metal is not microwave-safe and will spark, causing the glass to shatter. Finally, if you're using a colorful glass dish, make sure to look for a microwave-safe label or logo, as the dyes used to create the color may not be food-safe.

Microwave Safe Checks

Most glass dishes are now microwave safe, and you can tell for sure by looking for a microwave-safe label or emblem on the glass dish. But if you can't find one, there is a method for determining whether your glass dish is microwave-safe or not.

The first step is to increase the power of your microwave oven to its highest power setting. The next step is to fill a glass measuring cup or glass bowl halfway with water, then lay it on the glass dish in the microwave oven. Finally, make sure that the glass dish is empty.

Microwave both the cup and dish for 1 minute after they've been placed in the oven. It is not microwave-safe if the glass dish is warm or hot after being heated. On the other hand, if the dish remains chilly but the cup is hot, the glass dish is microwave safe. Also, while the area around the glass cups on the dish may be slightly warm, the rest remain chilly and are microwave safe.

Can You Microwave Cold Glass?

If you plan to microwave any food products taken out of the freezer along with the glass dish or container, you should check a few things before doing so. First, before moving frozen food to the microwave oven, make sure it has thawed to room temperature.

Condensation will form on the glass container when it is withdrawn from the freezer, so make sure to wipe it away before placing it in the microwave. If that isn't an option, let plenty of time for the dish to thaw slowly on low power.

When the microwave is turned off, use pot holders or cooking gloves to handle the glass dish to avoid getting burned by the heat transference and limit the chance of dropping the glass dish or container. Keep in mind that tempered does not imply indestructible. If you drop a microwave-safe glass on the floor, it will shatter.

How Does a Microwave Oven Work?

Inside the microwave oven is a magnetron, which is a vacuum tube. Waves are generated by the magnetron and reflected by the microwave oven's metal interior. These waves, which may flow through other materials, including paper, plastic, and glass, are absorbed by food.

These 'microwaves' are electromagnetic radiation. They generate heat by making liquid molecules vibrate, which cooks the dish. These waves, however, are non-ionizing radiation. To put it another way, unlike ionizing radiation such as X-rays, they cannot cause changes in human cells.

Microwave ovens work by activating radiation waves to heat food. These radiation waves affect any liquid before heating the solid components. Consider this the next time you want to take anything out of the freezer.

Materials to Avoid When Using the Microwave

Many bowls and plates are microwave safe. However, if you use the wrong dish, your dinnerware and your meal will be damaged. Before putting any dishes in the microwave, be sure they are microwave-safe dishes. Ceramic, which is burned clay, is not technically glass, but if labeled as such, it is microwave safe. If heated and then cooled too quickly, some glass-ceramic tableware may shatter; it will not be labeled as "microwave safe."

Some containers can break, melt, or scald you. Cook and store food in microwave-safe dishes. Containers that aren't microwave-safe can only be used for storage or serving. Some containers, such as foil-lined containers, can cause harm to your microwave. Metal containers, such as foil and metallic take-out containers, brown paper bags, dairy storage containers, and foam-insulated cups and trays, are not microwave-safe.

Some polymers can be used in the microwave, while others cannot. Unless it's labeled "microwave safe," avoid heating meals using plastic, especially plastic wrap. In the end, look for the words "microwave safe" on any containers before placing them in the microwave.

What Materials are Safe for Microwave Cooking?

The containers must be of a material that allows microwaves to flow through to the meal in order to be utilized in a microwave oven. You can use borosilicate glass in the microwave in any setting. It can heat, reheat, bake, or roast meals. You can also use tempered glass in the microwave. It's best for reheating and mild cooking.

Only use a regular soda-lime glass for reheating, not for cooking. For warming, thin ceramic is fine. The thicker one may heat up quickly. You can use corning ceramic glass in the microwave since it has the appearance of ceramic with the same properties as borosilicate glass.

Microwave-safe china and pottery, ovenproof glass, and glass-ceramic dishes are excellent choices. Fine bone china and regular glass, on the other hand, should only be used for limited periods since they will crack if exposed to too much heat.

Microwave-safe materials include paper cups, cartons, cling film, and thermoplastics. Metal or foil non-microwave safe containers should never be used since microwaves reflect off of them. Melamine ware also has a propensity for cracking when heated.

Microwave Glass Safety Precautions

Glass containers, cookware, and plates are not all made equal. Before microwaving a glass container, take these heating and safety precautions into account. Use only reputed brands of high-quality glass bakeware. When using a glass container, dish, or cup in microwaves, make sure the manufacturer has designated it as microwave safe.

If glassware isn't correctly labeled as microwave safe, test it. For example, if you're using a glass dish that isn't labeled as a microwave-safe container, run the test described above before microwaving the meal. Likewise, if you're using colored glasses, make sure they're microwave safe. Otherwise, the color may leak into your dish, making it unsafe to eat.

When microwaving glass containers, be careful not to overheat them. Overheating glass might result in damage to your cookware or convenient appliances. Instead, cook for 2 minutes at a time, stirring the meal in between. Also, metal-decorated glass should not be microwaved. Microwaving glass with metal ornaments is dangerous because the metal can spark and ignite, causing damage or a fire.

Glass containing air pockets or small bubbles should not be microwaved. The trapped air inside the glass can soon heat up and expand, cracking or shattering it. Likewise, cold glass should not be microwaved. Allow the glass dish to get to room temperature before exposing it to heat if it was recently removed from the refrigerator or freezer. If the cold glass is directly hit with high heat, it will crack.

The microwave's heating ability will be reduced if a dish is overfilled with food. It will be heated inconsistently, resulting in cold and hot food spots. Cooking time, temperature, and technique differ amongst foods. Heating food with different flavors or textures may result in an off-flavor or texture. To avoid such issues, stick to similar items and ensure that all of your microwaved meals are great.

When microwaving food, stir the food in the glass dish between each interval to distribute heat evenly across the dish, encourage even cooking, and shorten the overall microwave time. Before serving, food should be heated to a minimum internal temperature of 165 degrees Fahrenheit (74 degrees Celsius).

Ian Mutuli

About the author

Ian Mutuli

Founder and Managing Editor of Archute. He is also a graduate architect from The University of Nairobi, Kenya.