Vitrite

Vitrite is a very low fusing point black glass mainly used for the insulation base of electric lamps. It used to be made by the Vitrite Company. ^[1] Vitrite can be called foam glass because the mineral from which it is obtained is a spongy mass varying in colour from white to black depending on impurities. ^[2]

Process

To make the electric lamp, molten vitrite is poured into the shell up to a height of approximately a quarter inch (6 millimeters). A plunger is brought down to force the plastic glass into shape and fix the contacts.^{[ citation needed ]}

Composition

Vitrite is referred to as glass but in fact it is an enamel which contains a high proportion of lead (II) oxide to give fluidity, and considerable quantities of manganese oxide to produce a black colour.^{[ citation needed ]}

References

1. "'Vitrite' holders for incandescence lamps", Electrical Review, vol. 16, no. 378, p. 165, 21 February 1885.
2. Official Journal of the European Communities: Information and notices, vol. 41, Issues 287-291, p. 173, Office for Official Publications of the European Communities, 1998