In Messrs. Harper's establishment in New York, an improved wet process
of blackleading is adopted. The wax mould is laid face upward on the
floor of an inclosed box, and a torrent of finely pulverized graphite
suspended in water is poured upon it by means of a rotary pump, a
hose, and a distributing nozzle which dashes the liquid equally over
the whole surface of the mould. Superfluous graphite is then removed
by copious washing, an extremely fine film of graphite adhering to the
wax. This answers a triple purpose; it coats the mould with graphite,
wets it ready for the bath, and expels air bubbles from the letters.
This process prevents entirely the circulation of blacklead in the
air, which has heretofore been so objectionable in the process of
electrotyping.