A method of producing aluminum castings which includes the steps of casting a molten alloy, contacting the surface of the molten alloy with a humidified atmosphere and solidifying the alloy. The method is particularly suited for aluminum-magnesium alloys such as AA 5XXX and 7XXX series alloys. In addition to reducing the thickness of the surface oxide layer formed during casting, the method also provides improved surface quality of cast products and reduces subsequent remedial re-work or scalping. An improved aluminum-magnesium cast alloy product is also disclosed.