Wrap and Zap is a 100% cotton batting made by Pellon for use in the microwave.
sewingsuz- I have made four of these bowl holders and they all looked awful after washing. The first 2 I did and X from corner to corner then a circle in the middle, I also cut the batting the same size as the fabric. The second 2 I sewed and X corner to corner then a + from side to side and again a circle in the middle. W/these two I cut the batting 1" smaller and it did not get caught in the seam when I top stitched...mistake. They came out even worse than the first 2. So, I plan to, at the very least, preshrink the batting before making anymore. The package mentions that the batting will shrink, but does not say you have to preshrink. I just treated it like I would regular batting. If I were you I would wash one and see how it comes out, just in case...