Hand polishing glass – while
Hand polishing glass – while it can give you wonderful results — is a lot of work.
You can sometimes “cheat” and fire polish a slumped piece by putting it back into the mold. The trick is to heat the piece up to about 1000° F, hold there long enough to make sure the piece is heated throughout, then go as fast as possible to fire polish and as fast as possible back down to anneal. The idea is that you melt the surface without giving the interior of the glass enough heat to deform or pick up texture on the back side. The initial soak at 1000° F is to ensure you don’t thermal shock the piece.
As with all cheats, failure is a possibility 
Paul
FusedGlass.Org
Helios Kiln Glass Studio
PaulTarlow.com
