If you can afford a combination of cotton with natural silk or chiffon, those provide the best protection from coronavirus if you are not one of those people hoarding N95 masks.But, really, unless you are a healthcare worker, the kind of covering makes little difference. Even if you do spend the money for silk, you are unlikely to have a homemade mask fit well enough it is superior to a bandana. And if you are someone who touches your face often, they are all less effective. Your eyes are not covered. Critics are not wrong for wondering if homemade masks are more than placebo, since aerosols can easily slip through gaps in many cloth fibers.