Hot top composition for casting molds

Claim 1

A HOT TOP FOR CASTING MOLDS HAVING A HIGH HEAT RESISTANCE, A HIGH HEAT INSULATION ABILITY AND A LOW HEAT CAPACITY, SAID HOT TOP BEING A SELF SUPPORTING THIN-WALLED STRUCTURE AND CONSISTING ESSENTIALLY OF A HOMOGENEOUS COMPOSITION OF FROM 4 TO 12% BY WEIGHT OF A FINELY DIVIDED ORGANIC, HEAT-INSULATING FIBROUS MATERIAL SELECTED FROM THE GROUP CONSISTING OF PAPER AND PAPER PULP, FROM 2 TO 8% DRY WEIGHT OF AN ORGANIC GLUE, UP TO 10% BY WEIGHT OF REFRACTORY FIBROUS MATERIAL, FROM 70 TO 90% BY WEIGHT OF A FINE GRAINED SUBSTANTIALLY NON-POROUS, REFRACTORY MATERIAL HAVING A BULK DENSITY IN ITS UNCOMPACTED DRY CONDITION GREATER THAN 3.5 KG./LITER SELECTED FROM THE GROUP CONSISTING OF OLIVINE, SILICA, SILICATES, MAGNESIUM OXIDE, SLAGS, FLY ASH AND BALL MILL DUST AND FROM 3 TO 15% BY WEIGHT OF A FINE GRAINED, POROUS REFRACTORY MATERIAL HAVING A BULK DENSITY IN ITS UNCOMPACTED DRY CONDITION OF LESS THAN 0.3 KG./LITER SELECTED FROM THE GROUP CONSISTING OF INFUSORIAL EARTH, VERMICULITE, DIATOMACEOUS EARTH AND KIESELGUHR.