Some blackout material can be made with toxic, harmful chemicals, so it's important to carefully read what material they're made out of before you make your purchase. You'll know that these chemicals exist if the liners have an off-gassing smell, or are musty when you take them out of the pack. Our products on this list are mostly made of 100% polyester, which is a safe material for the bedroom. Aside from polyester, microfiber is also a great fabric for blackout liners, particularly if they're triple-weave.