I made a baked potato bag and was careful to use only 100% cotton fabric and I used the special batting made for microwaves. Last night, the bag caught fire in my microwave and the only thing I can think of is the thread may not have been 100 % cotton. I can't check as I have no idea which thread I used but the burn seemed to have started by the seam. Is that possible . Any thoughts ?

I do not put any covering on potatoes that I bake, so I cannot help.

now i wish i'd kept an old potato bag a friend gave me. worked well. I moved and gave it away. I'm now back to the oven.

I've heard about them catching fire many times. Don't use them.

I've heard of many fire disasters even with 100% cotton everything. It's my theory that anything will burn if it is in the microwave too long.

I do not use anything other than a paper towel, so I have no advice either.

Is there a benefit to them? I just wrap mine in paper towels to microwave.

Not worth putting your house on fire. Please stay safe.

It's not the fabric or batting most of the time. There was probably a hot spot in the microwave. I've noticed lower wattage microwaves have hot spots. You ever put more then one food item on a plate and have one not be as hot as the others? That is uneven heating and will cause hot spots. A 1200 watt will cook a baked potatoe in a couple of minutes. A lower wattage will take up to 12 minutes thus the hot spots get hotter for a longer time.

So, you believe cotton is non-combustible?

To this day, I don't understand why people think those bags are a good idea.