The situation is (I believe) that we are actually looking to damage the feathers to a certain extent. We use the bleach to 'burn' the fibers of ........for instance goose shoulder feathers. The process burns / removes the fine zipper like barbs that hold the feather fibers together. By doing this we are producing long feather fibers that flow nicely on many wet fly patterns.
Ard, Thanks for the explanation! Very interesting! Controlled damage. Not something I've done as I've never had the need to do this. I have used bleach to strip the fine fibers on peacock herl when quills were needed for a body, but not in the manner you've described. Learned something new!
What I described is more for removing color where you don't wish to damage the fibers.