So if you want to use a filter, you need to sandwich the filter between two layers of cotton fabric. Dr. Wang said one of his grad students made his own mask by following the instructions in the C.D.C. The best-performing designs were a mask constructed of two layers of high-quality, heavyweight “quilter’s cotton,” a two-layer mask made with thick batik fabric, and a double-layer mask with an inner layer of flannel and outer layer of cotton. A simple light test can help you decide whether a fabric is a good candidate for a mask. “If light passes really easily through the fibers and you can almost see the fibers, it’s not a good fabric.

Source: International New York Times April 05, 2020 09:00 UTC