Imparting matt finish to external surface of electric lamp bulbs - by rumbling lamps in aq. suspension of boron carbide or silicon carbide abrasive

摘要

The finished lamps, complete with their pinched glass or vitreous silica feet from which the contact wires project outwards, are placed in a rotary drum contg. a suspension (I) of an abrasive employed to produce a frosted finished on the bulbs. Suspension (I) is pref. chemically neutral and consists of boron carbide or silicon carbide in water. The extent of the matt or frosted finish is pref. controlled by either the treatment time in the suspension (I), or by the grain size of the abrasive particles in the suspension. The frosted lamps are used e.g. as signal or display lamps in appts., esp. for illuminating graduated scales. Several thousand lamps can be treated simultaneously.