Down proof wash bag fabric

[1shot]

As a casual duck hunter I realized the other day while cleaning some ducks that I throw away a lot of down that might otherwise go to good use. I also have several friends who hunt ducks and geese who will give me their breast and back skins with the down and pin feathers. I have a plan to separate and sort the down but I still need to figure out how to clean and sanitize the plumes. I recently purchased a good front loading washer/dryer set that I will use to clean, sanitize, dry, and fluff the down and feathers before separation if I can find a way to reliably protect my machines from the down. I figure I'll make a roll top or zippered bag to wash the down in. Question is, what is a good fabric to make the bag from that will keep the down inside while also allowing the water in and out to do its job? Any other knowledge on down processing would be great.

Thank you,
Jeff