Toss a piece of batting into the microwave and test cook it. Don't use any without testing first.

I was gifted a microwave cozy & it was a while before I started using it for my morning oatmeal. Now I can't do without it! I've been wanting to make some for Christmas gifts, but when I inquired about what the maker of mine used for batting, she didn't reply. In the meantime, a friend of mine went to a craft show before Christmas & bought one for herself & one to give her mom. She loves hers, but wanted a bigger one. So I bought the batting for microwaving & followed directions for making it, & I discovered that the bowl is thicker than the one I was given, & also thicker than the one my friend bought at the craft show. However, she loves it & I know hers won't catch fire -- I'm just not sure about the others!

I would not dare make these cozies with any other batting. I still don't know how the others were made -- did they use just one piece of batting? I used two.

Also important use 100% cotton fabric and 100% cotton THREAD...

microwave bowls
 

It will work, but you are taking a chance of it catching fire. The thermal stuff you use is the best bet.

I used warm and natural in mine and have never had a problem and I've been using mine for a couple of years almost daily

I use my microwave bowls almost daily. I love them. I used 100 % cotton, warm and natural, double layers. I've used/washed and dried them, and the only suggestion I have for myself if I make more is to do a little more quilting on them so when they are washed they don't shrink up as much. The last time I washed mine, I molded it back over the bowl I always use in it.

NO! I recently read an article about/by Warm and Natural where they discontinued the batting originally made for microwaving. In the article it stated that there was no guarantee that the batting wouldn't catch fire. Sorry but I don't have a link (and the memory isn't what it once was). I was going to make some bowls and decided against it after reading this. Better error on the side of caution imo.

I agree with tesspug, using 100% cotton batting, such as Warm & Natural works well. I tried one out and plan to make more for gifts and some for a craft fair I'm going to the end of June.

Read somewhere that with 100% cotton batting, fabric & thread, you still need to limit the time in the microwave to under 8 minutes -- and NOT use the bag again until after it cools all the way down. Made my own, it's all 100% cotton, and use it for 2 medium size potatoes only -- with a 1000 watt m/w, it takes 5 minutes, let sit in bag about 5 more. Wash, but hang to dry. So far so good...

I use the bowls but never heat them for more then 2 min. If it takes longer then 2 min to heat a bowl of food soup you need a new microwave. I don't use any batting product to cook anything in the microwave, only for heating up.