FIELD: foundry, possibly manufacture of molds and cores with use of gypsum binder for making castings of ferrous and non- ferrous alloys. SUBSTANCE: method comprises steps of preparing flowable molding sand, vibration vacuumizing of it, casting, solidifying, surface drying, impregnating it with solution of concentrate of aluminum-boron phosphate and subsequent hardening. Molding sand is subjected to surface drying for making porous surface layer at heating it in drying chamber at (150-200)C for 1.5-2 hours or at drying in air for 8-10 hours. Sand is impregnated with above mentioned solution by depth (1-5)10-3m. EFFECT: increased strength of cores and molds at hardening and pouring high- temperature melts while keeping their high capability to knocking out. 4 cl, 1 tbl, 1 ex
