Review on Cotton Sateen Blend Pillow Protectors 20x30 Queen Size - 4Pack | Lab Tested 450 🛏️ Thread Count | Tight Weave | ❤️Life Time Replacement | Premium Quality | Non Noisy Zip by Josh Payton

Burning a piece of cloth will produce thick black smoke and a hard plastic deposit that definitely contains polyester. Also, a win-win option is that the fabric cannot wrinkle - 100% cotton will always wrinkle. It also has a regular invisible zipper, no overlaps, fabric tabs or other restrictions so I don't see how it could be mistake proof, but the zipper comes very close to the end so if you're careful close it. Well, a random bug probably won't make it through, but a determined and repulsive little maggot might. But still 4 stars because they are very well made and the fabric is of good quality and tightly woven, so probably suitable for people with allergies. I use them to store wool and cashmere sweaters (as they are breathable) in plastic containers and think the poly content will keep carpet bugs and moths away (as they like natural fibers). If you have a hot head I would look for 100% cotton.