The characteristics and invention methods of the sticky sand defects caused by the modeling and core making of cast iron platforms: The surface iron liquid of the casting is stuck with sand, forming a rough surface, which can be found by the appearance inspection method. Cause analysis: 1, the compactness of the sand mold is not uniform or too small. 2, the coating is brushed too thin. Preventive measures: 1, appropriately increase the compactness of the molding sand, reduce the gap between sand grains, and consolidate evenly. 2, choose appropriate coatings, and brush them with a certain thickness, for cast iron platforms, which can not only improve the fire resistance, but also prevent the iron liquid from penetrating into the sand grains.