How to remove the fluorescent coating from lamps?

Question

I assume it is made of some mineral salts that could be removed by chemical action where polishing cannot reach.

Answer 1

The white fluorescent coating is on the inside.  It is usually a mixture of lanthanide (Eu and Tb) oxides; different oxides fluoresce in different colors, so a mix is used to give white light.  The coating can probably be dissolved by concentrated acids (sulfuric and/or nitric, maybe hydrochloric?).

The coating is probably toxic to some extent, and the glass may also contain traces of mercury.  Use of concentrated acid is extremely dangerous.  If you only want the lamp (bulb) as an interesting shape, it might be easier and safer to simply blow regular glass into the shape you want.