Separating Down from Feathers

Does anyone know of a good way to separate down from the feathers from a duck or goose that is being plucked? When plucking waterfowl by hand it is at least reasonable to pick each separately although there is still some mixing. We are considering a machine plucker which would make separation of the types much more difficult. It seems there must be some sort of existing method since one can buy articles of clothing or bed linens made of down only with few, if any, feathers mixed in, but my searches have not uncovered it.

Hi Carl!
I can't offer any advice, but I do want to welcome you to Permies! If you get a chance, we'd love to get to know you better. We have an Introductions forum where you can introduce yourself. I trust you'll learn as much here as I have.

If you're talking about the pluckers they use for chickens, it's my understanding they don't work well, for ducks. I'm not sure if it's how the fathers are Atwater, or if it's because duck fathers contain more oil, or if it's something else, entirely. But, I'd probably look into it, before buying one.