Wally Wing pattern tied with duck feathers

Wally Wing pattern tied with duck feathers

Catskill style Hendrickson tied with teal feathers

Catskill style Hendrickson tied with teal feathers

CDC used in a nymph pattern

CDC used in a nymph pattern

When buying CDC it typically comes in packages and will either be sorted/graded or not, they can be dyed, and feathers can be categorized into large, medium, small or oiler puffs/tufts. The larger CDC is more expensive (because ducks do not grow as many) and can be used for wrapping around a hook shank to create bodies, twisting into a dubbing loop to make a variety of things, forming bigger wings, and many other applications. Goose CDC could also be a substitute for larger duck CDC feathers.

Medium to smaller CDC are good for para loops, collars for nymphs and wet flies, small wings and emerger wings, etc. The oiler puffs/CDC tufts are tiny feathers that lack any sizable stem and are great for emerger wings and wing cases.

One final thing about CDC, when you use a fly that has CDC and it starts to get water logged or slimy from a fish's mouth it is best to use CDC-specific floatant oil (like Veniards CDC Oil), an amadou patch, or dry fly desiccant. Typical floatants like Gink just mat down the fibers and reduces the CDC's effectiveness to float.