craftgrrl | Microwave-Safe Fastenings? (Reply)

Hello crafty folk!

I looked through the memories, but I couldn't find the answer to this exact question...

I'm planning on making a microwave bag/neck wrap similar to the one

drowningmermaid posted recently. I'm planning to make it out of flannel with a fleece cover that can be removed and washed.

I'm concerned, however, about the inner flannel bag and the beans/rice that will be in it. My grandmother made me a rice bag some years back, but it was invaded by beetles that crawled inside and reduced the rice to dust, and made the whole thing completely unusable. Keeping this in mind, I'd like to incorporate some kind of opening in the inner flannel bag so that the filling can be changed periodically, and the bag washed to prevent this from happening again.

So here's my question: what kind of fastening would be safe to use in the microwave, but would be secure enough to keep the filling from spilling out everywhere? I don't plan on using a metal zipper, obviously, but what about a nylon one? Or velcro? Would those just melt?

Thanks in advance for any ideas you can offer! :)