an apparatus and method for forming foundry cores and molds of superior hardness and uniformity in a wide range of sizes includes staging hoppers for storing a first mass of sand coated with a catalyst - polymerizable resin film , and a second mass of sand coated with a catalyst film for polymerizing the resin . in forming the cores or molds these masses are evenly dispersed into a high velocity carrier air - sand stream and directed through a static mixer , wherein the resin and catalyst - coated sand particles are intermingled and at least a partial integration of the films takes place , into a shaping mold cavity , wherein the sand mixture hardens into a desired shape . control circuitry is provided to independently control the dispersal of the catalyst and resin sand masses to enable the system to be fine tuned to produce cores of improved quality and uniformity .