too much foil can damage your oven, so be careful. You should keep distance of 1 inch (2.54cm) between aluminum foil and cavity.
Ceramic, porcelain, and stoneware— Use these if they are labeled "Microwave Safe". If they are not labeled, test them to make sure they can be used safely.
Plastic — Use only if labeled "Microwave Safe". Other plastics can melt.
8Not Recommended
Glass jars and bottles — Regular glass is too thin to be used in a microwave. It can shatter and cause damage and injury.
Paper bags — These are a fire hazard, except for popcorn bags that are designed for
microwave use.
Styrofoam plates and cups — These can melt and leave an unhealthy residue on food.
Plastic storage and food containers — Containers such as margarine tubs can melt in the microwave.
Metal utensils — These can damage your oven. Remove all metal before cooking.
Note:
Should you wish to check if a dish is safe for microwaving, place the empty dish in the oven and microwave on HIGH for 30 seconds. A dish which becomes very hot should not be used.
COOKING TECHNIQUES 
Your microwave makes cooking easier than conventional cooking, provided you keep these considerations in mind:
STIRRING
Stir foods such as casseroles and vegetables while cooking to distribute heat evenly. Food at the outside of the dish absorbs more energy and heats more quickly, so stir from the outside to the center. The oven will turn off when you open the door to stir your food.
ARRANGEMENT
Arrange unevenly shaped foods, such as chicken pieces or chops, with the thicker, meatier parts toward the outside of the turntable where they receive more microwave energy. To prevent overcooking, place delicate areas, such as asparagus tips, toward the center of the turntable.
SHIELDING
Shield food with narrow strips of aluminum foil to prevent overcooking. Areas that need
shielding include poultry wing tips, the ends of poultry legs, and corners of square baking dishes. Use only small amounts of aluminum foil. Larger amounts can damage your oven.
TURNING
Turn foods over midway through cooking to expose all parts to microwave energy. This is especially important with large foods such as roasts.
STANDING
Foods cooked in the microwave build up internal heat and continue to cook for a few minutes after heating stops. Let foods stand to complete cooking, especially foods such as cakes and whole vegetables. Roasts need this time to complete cooking in the center without overcooking the outer areas. All liquids, such as soup or hot chocolate, should be shaken or stirred when cooking is complete. Let liquids stand a moment before serving. When heating baby food, stir well at removal and test the temperature before serving.
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