Hello,
First to reply to the question of CDC puff, they are small feathers (1/2" to 3/4") which are directly around the tip of the preen gland. They have no rachis and can be used on small flies as wing. Being on the preen gland, they are often saturated with CDC oil.
The question of dyed CDC flotability against natural unwashed CDC is asked regularly.
As already said in previous post, it is more the feather micro-structure which make the feather float than the oil. Further, the oil on the natural feather degrades rather quickly (oxygen and light) and wouldn't help.
And finally, you can use floatant with flies: CDC oil is one (use very very little) and hydrophobic powder is another.
For more info,: http://www.pechetruite.com/Boutique/...rd-feather.htm