Don, I have never found the need to wash a feather, any gunk can easily be brushed off with an old, used, soft bristled tooth brush. I bag them up and throw in a couple moth balls. I have some that are ten or more years old and look as good as the day I put them in the bag. You can go years without a moth problem, but once you get them, you got them, an ounce of prevention...... as they say. One good way to accumulate a lot of turkey feathers is to make up a flier, the cooler, more attractive and eye catching the better, make copies and put them on bulletin boards where ever hunters might occasion, like the local gun shop, archery range, gun range, even the supermarket if they have a community bulletin board. I think most hunters are glad to find someone that will use these beautiful feathers, heck I could never kill enough turkeys to fill my need, but after posting my flier I had guys dropping off bags of freshly harvested prime wings! I'd come home from work and find bags of them on the porch, or walk out the door and find those plastic shopping bags hanging off the side mirrors on my truck, couple minute's with a pair of side cutters and in the bag they go! Most of the time I never saw or met whoever it was that left them, or I'd be at the Archery range and some stranger would walk up to me and ask if I got the wings they left! Before I knew it I had trash bags full of first class wild turkey feathers, Oh, and Canada goose feathers too.
Robby