We do not use any glue to secure our feathers to the toy, only friction and tension. A very common question is "won't they just come out?" The answer is yes and no. No in that during normal play sessions the feathers will not come out of their holder. Yes in that when you need to replace them, simply just pull them out.
There is a fine line between too-much and not-enough tension. We want to be able to replace the feathers if necessary without needing glue or anything sticky.
The 60 mph feather test not only confirmed that the feathers would not come out of their holder, but that the swivels worked good enough to keep the string from twisting, tangling or coming unraveled.