I've had this happen to me one time where I used duck tape, wrapped it tight and it ended up turning the stem to mush in the covered area and killed it.
This year I've had a few branches snap down due to weight + wind. I couldn't believe that the branches were still living because the core of the stem and probably 75 percent total of the break area was exposed and not attached. I propped up the branches with stakes and twine for support and then loosely covered with tape so it could breathe. It's worked like a charm.