Abstract: The following method is used for manufacturing a vacuum-type circuit interrupter that comprises: (i) an envelope comprising a glass casing and an annular metal disc imbedded in the glass and (ii) a tubular metal shield mounted on the disc. The shield is first located within the tubular casing and then fastened to said disc, thereby forming a shield-envelope subassembly. This subassembly is attached to the table of a vibrator. The vibrator is then operated to vibrate the subassembly, thereby producing between the glass casing and the shield force that acts to flex the disc, thus removing loosely-adhered glass particles from the disc. Then the subassembly is removed from the vibrator table, rinsed, and used in a conventional manner to complete the interrupter.