Microwaves are common kitchen appliances that can be useful to warm and cook different foods in a quick manner. Yet many items should be kept away from this appliance at all costs, for a variety of reasons. Learning about the following 7 things you should never microwave can keep one safe, and the device working well.

1.) Metal

Any type of metal should never be microwaved. Foil, canned food, plates with a metal rim, silverware and metal pots and pans should never be used in the microwave. Using metal will result in sparks emitting from the item, as well as the possibility of damaging the microwave.

2.) Plastic

Many people store their leftover food in plastic containers that came from other food products, such as cottage cheese or yogurt. These plastic containers should never go into the microwave. Unless the container is marked "Microwave Safe," it is not safe to use. Microwaves cook the outside of food before the inside. The plastic container, located outside of the food, may get too hot before the food is properly cooked and melt. Aside from the melting potential of plastic containers, there are other concerns. Bisphenol A (BPA) may be released into the food from the container while microwaving. Always check the bottom of the plastic container to make sure it is microwave safe before using.

3.) Styrofoam

Restaurant leftovers are often brought home in styrofoam containers. These leftovers should be transferred to a separate plate before cooking. Styrofoam containers should also never be microwaved, unless marked as safe. These objects can melt if cooked for a long period of time.

4.) Paper

Paper bags from the grocery store can emit toxic fumes from the ink and glue in the bag, as well as start fires. Brown paper lunch bags are designed to come into contact with food and are a safer alternative to place in the microwave for short periods of time.

5.) Grapes

It may seem like a good idea to dry grapes in the microwave in order to make raisins, but grapes should never be heated in the microwave. Doing so can cause the grapes to burst into flames, which can also cause harm ether the user or the microwave. Raisins should also never cook in the microwave. Most other types of fruit are okay to microwave. Before microwaving fruit though, pierce with a fork or small knife to allow for the steam to release during cooking.

6.) Eggs

Don't try to save time by trying to "hard boil" eggs in the microwave. The waves quickly heat the water content in the egg, resulting in steam building up without a way of releasing. This can result in the egg exploding, causing quite a mess.

7.) Nothing

Microwaving nothing at all can also ruin the appliance. Microwaves work by using radio waves to agitate the water frequency in food. When there is no water to agitate, there is nothing to absorb the waves. The magnetron in the microwave, which makes the radio waves, absorbs them. If the magnetron absorbs too many waves, the microwave will break.

Staying safe and keeping the microwave running is easy to do by following these suggestions. Doing so will save time and electricity, and result in warmed food that is safe to eat.