Locking Hemostats also work for grabbing the hollow key shank, instead of bead release. I don't have a good pair for keys, so I use the bead release. I also prefer the key to be on the same axis as the mandrel.
You can drip or carefully pour the release into the opening of the key's barrel , then insert a dipped mandrel. The excess release will drip out the end of the mandrel. Gently heat the key in a low flame while the bead release dries. The air will bubble out on it's own
The technique also works great on stainless steel thread bobbins. A student and I tried it last class session. Too fun!