I am sorry I didn't read this entire thread instead of jumping in midway. I have removed several warts and a mole with bloodroot. It is a very difficult process, painful and it takes a long time. The wart on my neck came back and I tried removing it again. Took even longer and was more painful the second time. Wart came back again. That is when I realized I would have to take a systemic approach to beat this, and started taking bloodroot powder internally.
Can you post a picture? Are you just trying to get the eschar to let go? The one on my neck hung by a string like fiber for a while. This is not uncommon. Take care not to break the thing. Maybe you could spot treat around the tissue that is hanging on. I would definitely do this in conjunction with a systemic approach. Get him on Red Clover/Stillingia tea if he cannot tolerate bloodroot internally.