Microwaves have become an indispensable appliance in most kitchens today. They offer a quick and convenient way to heat up leftovers or prepare a hot meal in minutes. However, not all materials are safe to microwave. Some items can cause sparks, start fires, or even explode if microwaved. So it’s important to know what you can and cannot put in a microwave.
In general, microwave-safe cookware should be made of material that does not contain metals which can reflect microwaves. Good microwave-safe materials allow microwaves to pass through and heat up the food inside. Three of the safest materials for microwave use are:
Ceramics
Ceramic cookware is one of the most common types of microwave-safe dishware. Items like plates, mugs, bowls made of ceramic clay are ideal for microwave heating. The porous nature of ceramic allows microwaves to penetrate the material and heat up any food inside. As long as the dish does not contain metallic paints or decorations, plain ceramic cookware is safe in the microwave.
Glass
Glass is another microwave-safe option for cookware. Glass dishes, containers, and mugs are safe for microwave use as long as they do not contain metallic paints or details. Glass allows microwaves to pass through and heat up the food. Tempered glass cookware is best as it can withstand sudden temperature changes in the microwave better than ordinary glass.
Plastic
Certain types of plastic containers, wraps, and dishes are labeled “microwave-safe.” These plastics are specifically designed to not melt or leach chemicals when exposed to microwave radiation. Look for the microwave-safe symbol on plastic cookware before using. Polypropylene plasticware is one of the most microwave-safe options.
Avoid using plastics with recycling codes 3, 6, and 7, as these may contain chemicals unsafe for microwave heating. Code 2, 4, and 5 plastics labeled microwave-safe are better options.
Why Metals Should Be Avoided
Metals are unsafe in the microwave because they can reflect microwaves instead of allowing them to pass through and heat the food. The reflected waves can then build up intensity within the oven cavity. This concentrated energy discharge can damage the appliance itself or ignite any flammable objects.
Some examples of metallic items to keep out of the microwave:
– Aluminum foil
– Metal cookware and bakeware
– Dishes or mugs with metallic paint or detailing
– Metal twist ties and fasteners
– Silverware and kitchen tools with metal parts
If sparks, arcing, or other damage occurs inside your microwave, metal objects are likely the cause. The reflective properties of metals make microwaving them very dangerous. Even small pieces of aluminum foil can cause issues if accidentally microwaved.
Microwave-Safe Cookware Guidelines
When selecting cookware for microwave use, follow these guidelines:
– Choose non-metallic materials like ceramic, glass, and labeled microwave-safe plastics
– Avoid metal bakeware, cookware, dishes, utensils, wrapping, etc.
– Do not use recycled or antique ceramic and glassware, as these may contain metallic components
– Ensure dishes do not have metallic paints, gold rims, or other metal detailing
– Use lighter weight cookware, as heavier pieces may not heat evenly
– Choose round or oval dishes rather than metal-edged square baking dishes
– Look for the “microwave-safe” label on plastic containers
– Do not microwave empty containers; the lack of food may cause damage
– Avoid containers with metal lids or snaps; only use plastic lids or covers
– Use paper towels, wax paper, or microwave-safe plastic wrap to cover dishes
– Never microwave Styrofoam, cardboard, or paper, which can melt and burn
Foods Not Recommended for Microwaving
While most foods can be microwaved, some are not recommended because they may overheat, burn, or even catch fire in the microwave. Foods to avoid or use cautiously:
– Eggs – Can easily explode due to steam buildup inside shells
– Hot dogs, sausages, other meats with skin – May split and spray hot juice
– Marshmallows – Can melt and burn quickly
– Popcorn kernels – May scorch without constant stirring
– Deep-fried food – Likely to get soggy rather than crispy reheated
– Dried food – Can quickly burn if microwaved too long
– Whole tomatoes, squash, potatoes – May burst from steam buildup
– Baby food – Can heat unevenly and burn baby’s mouth
– Breastmilk, formula – Risk of scalding since liquids heat very quickly
– Frozen dinners – Often contain metal foils and finishes unsuitable for microwaves
– Canned foods – Metals may lead to arcing, burning, or plasma fires
When uncertain if a food is safe for the microwave, it’s best to follow package instructions or look up guidance online. Gradual heating, frequent stirring, and lower power settings can help minimize risks.
Microwave Power Settings
Microwave ovens today typically offer power levels ranging from 10% to 100% strength. Lower settings can be used to warm delicate foods safely. Higher levels quickly boil water or reheat dense foods. Adjusting the power settings based on what you are heating is important:
| Power Level | Best Uses |
|---|---|
| 100% (High) | Boiling water, cooking fresh vegetables, searing meats, reheating meals |
| 90% | Cooking oatmeal, rice, pasta |
| 80% | Reheating sliced meats, poultry, fish |
| 70% (Medium-high) | Cooking scrambled eggs, baked potatoes, stewed fruits |
| 60% (Medium) | Melting butter or chocolate, baking cakes |
| 50% (Medium-low) | Gently heating milk, cooking cheese dishes |
| 40% | Softening ice cream, thawing breads |
| 30% | Thawing meat, fish |
| 20% | Taking chill off refrigerated foods |
| 10% (Low) | Softening butter, defrosting delicate desserts |
Using lower power for a longer duration is gentler than blasting food on high. This allows time for thorough, even heating. Consult cookbooks and recipes for recommended power levels whenever possible.
Microwave Cooking Tips
To safely and effectively use your microwave:
– Double check that cookware is microwave-safe before heating
– Use plastic wrap or paper towels, not aluminum foil, to cover dishes
– Cut food into smaller pieces to allow for thorough cooking
– Arrange food in a ring around the outer edge of the turntable for best heating
– Stir and rotate food several times during cooking for even heating
– Allow standing time after cooking so food finishes cooking through
– Use an instant-read thermometer to check temperatures of meats and other foods
– Adjust power levels and cooking times based on quantities and densities of foods
– Heat liquids on lower power settings to prevent explosive boiling
– Let microwaved food stand 1-2 minutes before consuming, to avoid burns
– Clean the interior regularly to avoid any buildup of food debris
Following basic precautions is key to avoiding damage and improper cooking. With some trial and error, anyone can master safe microwave usage.
Microwaving Dos and Don’ts
Do:
– Rotate dishes during heating for even cooking
– Cover foods with vented lids, paper towels, or plastic wrap
– Double check cook times and power levels
– Allow standing time for thorough heating
– Check internal temperatures of heated meats and poultry
– Use microwave-safe thermometers to check food temps
– Follow package instructions for frozen meals and foods
– Use lower power levels for gentler heating
– Stir liquids and spoon sauces over foods mid-cooking
– Let microwaved foods stand before consuming
– Keep the interior clean of food splatters
Don’t:
– Use metal pans, aluminum foil, or dishes with metallic paints
– Operate the microwave empty or without the turntable
– Microwave whole eggs, hot dogs, or sausages
– Heat breastmilk, baby bottles, or baby food without stirring
– Microwave popcorn without a popcorn popper device
– Reheat whole potatoes, squash, tomatoes, or hot peppers
– Heat deeply frozen foods without defrosting first
– Use Styrofoam, plastic foam, or cardboard containers
– Operate with door open or tamper with safety interlocks
– Place foreign objects inside the microwave cavity
– Attempt to dry clothes, papers, or other non-food items
– Heat or can food in sealed jars or airtight containers
– Microwave for longer than manufacturer’s instructions
– Assume microwaved food is fully cooked without checking
Simple microwave safety comes down to using suitable cookware and some cooking common sense. Following basic guidelines will allow you to harness the speed and convenience of microwave cooking without any risks.
Conclusion
Microwaves provide fast, convenient cooking and reheating of foods when used properly. The key is choosing appropriate microwave-safe cookware and knowing what foods require caution. Ceramics, glassware, and some plastics labeled microwave-safe are good choices. Metal bakeware, dishes with metallic paints, takeout containers, and aluminum foil should be avoided. Foods that are prone to splattering or overheating require lower power settings and frequent stirring. With some basic safety knowledge, anyone can master microwave cooking to quickly prepare delicious meals and leftovers. Following proper usage guidelines will keep your microwave running safely for years.