|
The principal object in fine casting
is to have a mould that shall receive a beautiful impression, and
at the same time sufficiently adhesive to resist the force of the
fluid metal, that shall neither wash nor be injured by the heat.
The sand that covers or surrounds the model should be fine, close
sand; after removing the mould, the model must be faced with burnt
rotten-stone, and covered with loam, each dusted through a bag,
and the mould laid down upon it; this facing may be repeated, the
mould must be dried and smoked with a torch; in lieu of water, the
sand is moistened with a solution of tartar, or the lees of wine,
or with cream of tartar. Care must be taken to loosen the band quickly,
viz.: loosen the first mould while the second is pouring, etc. On
removing the work, every particle of the facing should be carefully
scraped from the mould and thrown away. Part the moulds with coal
and black rosin
|
