Can You Microwave Glass?

While few of us love relying on the microwave for regular meals, it certainly comes in handy when you're running late for work or craving midnight leftovers. Of course, not all containers are microwave-safe. So can you microwave glass? Or will it end in disaster?

Can You Put Glass in the Microwave?

Most glass is microwave-safe. But some glass is not.

Microwave-safe glass can be placed in the microwave for extended periods without the risk of damaging the object or contaminating the food inside. Meanwhile, glass that is not microwave-safe is liable to crack or shatter.

How To Tell If Glass Is Microwave-Safe?

how to tell if glass is microwave-safe

The easiest way to tell if any object is microwave-safe, whether it is made of glass or not, is to check the care instructions. When it comes to dinnerware, these instructions are most often printed on the bottom of the item in question.

Some glass dinnerware will feature a graphic symbol — a microwave with three wavy lines inside — to indicate that it is microwave-safe.

In most cases, this is all it takes to know if something can safely go in the microwave. But what should you do if no such instructions exist?

There are other ways to determine if a glass object is microwave-safe. Use these methods at your own risk.

The most popular of these DIY methods involves microwaving an unlabeled piece of glass for around a minute.

The final temperature will reveal whether it is safe to microwave further. If the item is hot after a minute, it should not be used in the microwave. If it is cool or slightly warm, it’s probably microwave-safe.

The best option will always be to avoid placing any item in the microwave unless it is specifically labeled as safe to do so.

Tips to Safely Microwave Glass

Do Not Microwave Cold Glass

do not microwave cold glass

Glass is very sensitive to sudden temperature changes, even if it is labeled as microwave-safe. You should never place a chilled glass cup or dinnerware in the microwave.

Instead, allow the glass to slowly reach room temperature before microwaving. If time is of the essence, you’re best off transferring the food or liquid to a different container.

Check for Air Bubbles

Glass items containing air bubbles are at particular risk of bursting in the microwave.

The air inside these bubbles can expand when heated. This places stress on the glass from the inside and can result in the entire plate, bowl, or cup shattering.

Generally, these items will not be labeled as microwave-safe. But there is always a chance that bubbles will appear as a manufacturing error. It’s best to check your glass dinnerware before microwaving just to be safe.

Beware of Dye and Metal Accents

beware of dye and metal accents

Most glass is microwave-safe. However, many glass items feature additional materials that may not be okay to put in the microwave.

The most common of these materials, at least when it comes to glass cups and dishes, are dyes and metal accents.

Some dyes are not microwave-safe. Exposure to high heat may cause discoloration or physical damage to the glass item. In extreme cases, it can even result in the release of toxic fumes.

Most people know that metal cannot go in the microwave. A glass object with a metal rim or decorative overlay carries the same risks as placing a fork in your microwave.

Again, glass dinnerware containing these decorative elements will not be labeled as microwave-safe.

Final Thoughts

More often than not, glass is microwave-safe. But the risks of accidentally putting the wrong piece of glass in the microwave mean that you should still double-check before doing so!

In a pinch, you can conduct a simple test to determine if an unlabeled glass object is microwave-safe or not.

However, the best way to confirm an item is microwave-safe is to reference the care instructions printed on the bottom. These instructions will also let you know if the glass can go in the dishwasher or even the standard oven.

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