CDC means ' butt of the duck' in French. Actually these secondary feathers come from directly over the oil glands on the lower back above the tail. Ducks squeeze these oil glands and then preen themselves to keep their feathers oiled and waterproof. Commercially speaking....After washing and in some cases dying the oil is all but gone. I know...bummer!
But the CDC feather itself has millions of micro barbs on each fiber which attaches to the stem. The micro fibers trap air and prevent the feathers from absorbing water. They also are soft and wispy and move like few other types of feathers. Makes them perfect as a wing, legs, trailing shuck or hackle. I also like to add them to emergers and even weighted nymphs because the trapped air bubbles are a natural attraction to fish.
Watch my videos where I utilize CDC and you will see a number of ways you can use these. Trust me. Flies with CDC work. Fishers have used them for 300+ years for a reason.
Harvested from commercially raised barnyard ducks.