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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 |