Microwaves are convenient for heating food fast, but carefully choose the container in which you place the food before you nuke your next leftover meal. Some containers are microwave safe while others are not. If a container is not microwave safe, the container may melt from the heat and the food might absorb some of the container, rendering it unsafe to eat. Microwave-safe containers do not get hot from the microwave's heat. However, if you leave the container in the microwave long enough, it might still get hot from the heat from the food, which is safe and normal. Look for a "microwave safe" label or branding on the container.
Pyrex glassware is microwave-safe glass. Other glass sometimes has air bubbles that heat up in the microwave and may shatter, but pyres does not. The glass in Pyrex containers is heat resistant, so you can use it to warm up your food safely in the microwave, and the heat from the microwave will not heat the Pyrex glass. Avoid using Pyrex containers that have metal trim, as metal is not microwave safe.
Lexan is a type of plastic that is microwave safe and will not get hot from the heat generated by your microwave. Lexan is a hard and durable plastic that also does not react to oils like other plastic, so it will not stain or smell like food that has been stored in the container. It is a food-grade plastic, meaning that it is safe for food storage though, like any food grade plastics, you should never use it to store anything other than food. Also, if the lexan plastic container cracks, chips or becomes cloudy, you should replace it. Lexan will not last forever, but new lexan containers are safe to microwave and will not get hot from the microwave's heat.
Plastic Bags and Wrap
Several plastic resealable bags are microwave-safe containers that will not get hot from the microwave's heat. These include Ziploc brand bags that are 1 qt. or larger. The smaller bags are microwave safe, but the plastic is often too thin to withstand the heat caused from the hot food, so the bags become hot. Saran brand cling film is also microwave safe and will not get hot from the microwave's heat. Read the labels or ask the manufacturer before microwaving any resealable plastic bags or cling film.
Test the Container
If you are unsure if your container is microwave safe and will not get hot from the microwave's heat, you can test it. Place the container in the microwave for 30 to 60 seconds. If the container is lukewarm or cool, it is microwave safe and will not get hot from microwave use. If the container is hot, it is not microwave safe and will continue to get hot if you use it to heat food in a microwave.