Core box vent construction

The core box construction for molding resin laden particulate matter, comprising:

• (a) mateable core box sections;
• (b) blow tubes in one section permitting ingress of gasses and particulate matter;
• and
• (c) porous ceramic vents in the other section to permit egress of gasses only through said pores but having a pore size effective to prevent the egress of said resin laden particulate matter.

A method of making cores, comprising:

• (a) forming mateable core box sections with blow tubes permitting introduction of an air fluidized sand mixture into the interior of the mating core box sections, and further forming one or more ceramic core box vents in the exhaust side of the mated core box section to permit egress of air used to fluidize the sand mixture, said vents having a labyrinth of passages or pores smaller in diameter than that which allows intrusion of the grain size of said sand mixture;
• (b) blowing a sand and resin mixture through said blow tubes into said mated core box sections and prevented from exiting through said vents, said resin being curable to polyurethane by chemical reaction;
• (c) forcing a catalyst curing gas through said blow tubes to cure said sand and resin mixture again without migration of any of said sand through said vents;
• and
• (d) purging said core box sections with air introduced through said blow tubes and exiting from said core sand mixture via said vents.