A method for making curable casting resins having a high content of finely divided inorganic fillers and comprising esters of acrylic or methacrylic acid and organosilicon compounds used as adhesion promoters, which method involves mixing the liquid polymer precursor comprising acrylic or methacrylic esters with the organosilicon compound and with an alkylamine as a catalyst for the organosilicon compound, the finely divided inorganic fillers being incorporated into the resulting mixture in such amounts that the viscosity of the mixture does not exceed 10 Pa.sec, the resulting thixotropic suspension then being transformed into a completely deflocculated low viscosity suspension by being allowed to stand for a sufficient length of time at room temperature or by short term heating.