or FRITT, in the glass manufacture, is the matter or ingredients of which glass is to be manufactured when they have been calcined or baked in a furnace.

Frit by the ancients was called ammonitrum, of aquae, sand, and nitræ, nitre; under which name it is described by Pliny thus: Fine sand from the Volturnian Sea, mixed with three times the quantity of nitre, and melted, makes a mass called ammonitrum, which being rebaked, forms pure glass.

Frit, Neri observes, is only the calx of the materials which make glass; which, though they might be melted and form glass without being calcined, yet it would occupy a much longer time. Thus calcining or making of frit serves to mix and incorporate the materials together, and to evaporate all the superfluous humidity. The frit, once made, is readily fused and turned into glass. See Glass.

Making.