Molding composition and method

Claim 1

THE METHOD OF MAKING METAL CASTING MOLDS AND THE LIKE WHICH COMPRISES FORMING A LOOSE GRANULAR MASS OF SUBSTANTIALLY ZERO GREEN STRENGTH ON A PATTERN SURFACE BY POURING ONTO SAID SURFACE A DRY GRANULAR REFRACTORY MATERIAL, INDIVIDUAL GRAINS OF WHICH MOVE READILY OVER ONE ANOTHER SO AS TO FORM A TALUS SLOPE WHEN LATERALLY UNSUPPORTED, AND WHICH INCLUDES A DRY, GAS-ACTIVATABLE BINDER DISTRIBUTED AMONG AND BETWEEN SAID GRAINS, ACTIVATING SAID BINDER TO A STRONG BOND BY PENETRATING WITH AN ACTIVATING GAS THE RESULTING GRANULAR MASS WHILE ON SAID PATTERN SURFACE, REMOVING THE RESULTING BONDED GRANULAR BODY FROM THE PATTERN SURACE, AND REUSING THE PATTERN FOR REPITITION OF THE PROCESS. 2. IN A METHOD OF FORMING A GAS PERMEABLE BONDED CASTING MOLD AND A MOLD SURFACE THEREON ACCURATELY REPRESENTING THE SURFACE OF A PATTERN, THE COMBINATION OF STEPS COMPRISING FORMING A DRY MIXTURE OF GRANULAR REFRACTORY MATERIAL WITH A WATER-ACTIVATABLE BINDER WHICH, ALTHOUGH DRY SO THAT INDIVIDUAL GRAINS CAN MOVE FREELY ON ONE ANOTHER, CONTAINS BOUND WATER RELEASABLY BY REACTION WITH A GAS, WHEREBY TO ACTIVATE SAID BINDER, KEEPING THE MIXTURE DRY SO THAT IT IS POURABLE AT THE TIME OF USE, POURING THE RESULTING DRY GARNULAR MIXTURE ONTO THE SURFACE OF A PATTERN, PERMEATING THE GRANULAR MASS THUS FORMED, WHILE ON THE PATTERN, WITH SAID ACTIVATING WHEREBY TO RELEASE SAID BOUND WATER AND THEREBY TO ACTIVATE THE BINDER TO BOND ADJACENT GRAINS IN CONTACT THEREWITH, AND REMOVING FROM SAID PATTERN THE RESULTING BONDED MOLD AND WHEN IT IS BONDED INTO A COHERENT MOLD BODY, AND REPEATING THE PROCESS WITH THE SAME PATTERN. 8. THE METHOD DEFINED IN CLAIM 1 IN WHICH THE BINDER USED IS A CRYSTALLINE SODIUM SILICATE WITH NA2O/SIO2 RATIO BETWEEN 2/1 AND 1/1.2 AND THE ACTIVATING GAS IS CARBON DIOXDE. 34. THE METHOD AS DEFINED IN CLAIM 2 IN WHICH THE ACTIVATABLE BINDER IS A WATER ACTIVATATBLE ACRYLIC RESION AND BARIUM HYDROXIDEN OCTA HYDRATE IS MIXED THERWITH AND THE ACTIVATING GAS IN CO2.