Here’s another source of information on filter material and face mask design. It appears some brands of blue shop towels are a good filter medium. Face mask design pattern is supposed to be released next week. Business Insider article
Another unobtanium material. If you’ve got some in the garage you’re okay but you’re not likely to find any of the hydro poly blue shop towels anywhere online. Just a hint of utility in stopping covid and the raiders swoop in to stock up. Hopefully they’ll use them making masks for folks.