No on the peroxide. I have been experimenting with this some because I get some that are pretty dirty at times. I have done my own, with great success, but have been reluctant to do other peoples feathers so far. All I did was take the full feather before grinding, and move them around in some warm water with a little Dawn dishwashing liguid in them. Letting them air dry seems at times to make the feathers not want to lay back together just right, but using forced air and they fall right back into place. My problem is I don't have the time to force dry thousands of feathers......lol.
If you grind them first, they will curl up really bad, don't ask me how I know that.