A method for providing an electric field having a desirable configuration and strength for the electrostatic coating of phosphors on a fluorescent glass envelope at a controlled temperature comprising enclosing a fluorescent glass envelope with at least one electrically conductive charge retaining member at a desired temperature for the duration of the actual electrostatic coating operation wherein charged phosphor particles are attracted to the interior of the glass envelope and the charge is dissipated to the charge retaining member which remains substantially electrically isolated during the coating process. The process is most suitable adapted to an asymmetric fluorescent glass envelope.