What materials and utensils should I avoid using in the microwave?

You should never use aluminum trays, food cartons with metal handles, metal or metal-trimmed utensils, metal twist ties, paper bags, plastic foam, or wood in the microwave oven. Metal can cause arcing, paper bags and metal twist ties can cause fires, plastic foam may melt and contaminate food, and wood may dry out, split, or crack. (Page 10)