Serious question OK? Could you use Scotch guard to waterproof feathers?? Has anyone tried??

That's what I use.

I have and still use it, It works very well!! The stuff is scotch guard for outdoors if I remember right! I need to get some more for this coming fall!!  I usually treat feathers the end of aug or early sept just to make sure the smell is gone! But it only takes a week for the smell to go away!!   Test an arrow first to make sure it wont react with your fletch glue!

Been using it for a long time and it works very well.

I have been using fletch tape no reaction there.

DD