My FIL would pull the husks back, remover the silk and replace the husks, freeze in bags and in middle of winter have corn that tasted like it had just been picked. He microwaved it. Never used a bag to cook them that I know of.

Honestly, I haven't read everyone's responses so perhaps this has already been mentioned and questioned and if so, my apologies........

Did you happen to put any moist food in the bag to cook or did you just put the dry cotton and dry batting and dry thread in the microwave? It's the moisture on and in the food being cooked that helps the bag from NOT burning. Just a thought since I didn't see in you statement that there was anything.

Honestly, I'm not sure that DH moistened the bag or not. He doesn't seem to remember. I know our potato bag was dry when I tested it and it came out of the microwave after 5 minutes, absolutely fine. Perhaps we just got lucky.

pardon me for asking - but are you sure its ok (health wise) to nuke a zip lock bag? I know a few years ago they put out not to let plastic wrap touch anything with grease/fat - like meat while microwaving - can be cancerous(?). Think I'd rather do any one of the other ways mentioned here - naked, natural (husk), paper towel, waxed paper or fabric.

No, I would never use plastic. The corn bags were made out of cotton fabric.

I've made and sold hundreds of potato/corn bags and only 2 caught on fire. One person left the safety pin on it that held the instructions and the other hadn't been washed after making sweet potatoes (the juice is very volatile) in it. That's not the bags fault in either case. The food to be cooked has to be damp and you have to put a wet paper towel around the item. It's that moisture that not only cooks the food so lovely, it's the moisture that stops anything from burning. Put dry food in the oven, it will burn. Put dry food in a skillet or sauce pan, it will burn. Cooking needs moisture. Dry cotton will burn. You made your bag just fine with all cotton materials. Try it again and actually cook something with a damp, or just plain wet, paper towel wrapped around it and you'll end up liking it more than the ol' oven method or boiled method.