We’ll answer that question with another question: Is your flannel made from 100% cotton?
If you answered yes, then it can go in the microwave; however, if the flannel has metal, like buttons or snaps, the answer becomes no.
What type of material is your flannel made out of?
Check the label. When you read the fine print, you won’t find anything on the care instruction tag about microwave usage, but it should indicate whether it is made from cotton or a polyester or synthetic blend.
Fabrics made from artificial materials are generally not microwave friendly, including polyester, acrylic, nylon, spandex, or other artificial-type fabrics. They tend to have plastics in them that can melt in the microwave.
The only thing you really want melting in a microwave is food, like cheese on top of nachos.
Microwave heating bags are hot items these days.
You might be wondering about flannel because you want to put a heating bag in the microwave.
You may know them by such names as rice bags, magic bags, stress buster, corn cozies, heat packs,
and the list goes on.
Those bags covered in soft, smooth cotton flannel are even better, especially when it comes out warm from the microwave.
It’s kind of like a warm, cozy shirt right out of the dryer on a chilly day.
As a rule, clothing and fabrics weren’t designed to be heated in any type of oven, and microwaves certainly weren’t intended for fabric, but somehow it all seems to work when you combine it with uncooked food like rice, corn, oats, beans, barley, and flax seeds.
So remember: artificial fabrics don’t belong in a microwave. While natural fabrics, like 100% cotton flannel, are perfectly fine, especially when they’re used as coverings on a hot bag.