High class mold is required for high quality castings. At present, the demands on molding materials are being extended by adding the strict requirement of environmentalists. A suitable variant that meets both demands are green sand molds. The goal of the thesis is to repeatedly cast experimental castings into molds made of 4 types of green sand mixtures. The technological properties of the molds will be compared, the degree of bentonite degradation will be assessed and the surface quality of castings will be assessed according to the amount of adherent molding mixture.