Strong Facing
Facing-sand is termed strong or weak, in proportion to the amount of clay present, or the quantity of coal used in the mixture. See FACING-SAND.
Twelve hundred entries from the golden age of cast metal — how bells are founded, why brass is not bronze, what a cupola melts and a core withstands — by Simpson Bolland, the trade's great teacher.
Facing-sand is termed strong or weak, in proportion to the amount of clay present, or the quantity of coal used in the mixture. See FACING-SAND.