The microwave is one kitchen appliance that many people simply can’t do without. From reheating leftovers to cooking entire meals in a snap, this appliance is a lifesaver. But with all its convenience comes a long list of dos and don’ts. One of the most common questions is: Can you microwave glass Tupperware?
Most types of glass Tupperware are safe to use in a microwave. You can tell if your Tupperware is microwave-safe by looking for a label or a wavy lines symbol on the bottom of the container. If there isn’t one, you can do a quick one-minute test to be sure.
Glass Tupperware is becoming increasingly popular as people become more conscious of the chemicals often found in plastic and their potential impact. But before you start microwaving your food in glass Tupperware, there are a few things you should know. Let’s take a closer look at different types of glassware and how they fare in the microwave.
Can You Microwave Glass Tupperware & Other Glass Dishes?
Generally, glass is a microwave-safe material; it can withstand high temperatures, it doesn’t melt, and it doesn’t emit any harmful chemicals. These properties make it safe for food and an ideal choice for microwaving.
Most kitchen glassware manufacturers take advantage of these properties and make sure their products are microwave-safe.
Some of our favorite options include these 100% leakproof containers (on Amazon) and this 24-piece set of of glass containers from Bayco (also on Amazon).
However, there are certain types of glass used in kitchenware that aren’t meant to go in the microwave. These include:
Glass With a Metallic Trim
Some glassware, especially ceramic glass, comes with decorative metallic trim or painted details. While the glass itself may be microwave-safe, the metallic elements are not. If microwaved, they can cause sparks, damage your appliance, or potentially start a fire.
Your glinting wine glasses and sparkling water tumblers are made from crystal glass. This type of glass has a more complex chemical composition than regular glass. Unfortunately, it’s not as heat resistant and is absolutely not microwave-safe.
The dye used in tinted glass can become unstable at high temperatures and leach into the food as the glassware heats up.
Cheap glass is more likely to have impurities, air bubbles, or other imperfections. These affect how heat travels through the glass and make it more likely to shatter in the microwave.
How Can You Tell if Glass Is Microwave Safe?
All kitchen glassware manufacturers that sell microwave-safe products are required to put a label or symbol on their products. It can be a set of wavy lines, a box with wavy lines inside or above it, or a stamp saying ‘microwave-safe’ or ‘for microwave.’
You should be able to find one of these symbols on the bottom of your glass Tupperware or in some other inconspicuous spot.
But if your glassware doesn’t have any of these symbols and you think it might be microwave-safe, you can test it out yourself.
All you need is a cup (verified microwave-safe), the glass Tupperware in question, and a microwave. Fill the cup with water and place it in the microwave along with the glass dish; keep the dish empty. Then microwave on high for one minute.
Carefully feel the outside of the dish; if it’s hot, then your dish is not microwave-safe. However, slightly warm to the touch is normal and means the dish is safe to use.
The water-filled cup in the test is important because you’re not meant to heat an empty glass dish, or any dish for that matter, in a microwave. Without anything in the microwave to absorb the waves, they just bounce around inside and eventually build up enough heat to damage the appliance.
How Long Can Glass Be in the Microwave?
Generally, it is best to avoid warming up a glass container in a microwave for more than 3 minutes at a time.
But there’s really no definitive answer because many different variables, like the type of glass, the thickness of glass, and the power level of your microwave, all come into play.
Some specialty glass, like Pyrex (on Amazon) or heat-resistant laboratory equipment, may be able to withstand more time or heat. But unless you’re sure, it’s always better to be on the safe side and limit your microwaving sessions.
If you need to heat something up for longer, it’s best to do it in short intervals. Put the glass in for 2-3 minutes, then take it out, check the food, stir, and let it cool down for a minute before heating it up again.