The production of quality aluminium and its alloys are almost always conditioned by the selection of appropriate technological processes, in the stage of melting the material, as well as its further processing. The well-known affinity of aluminium for oxygen spontaneously and constantly influences the appearance of many oxide inclusions, which, together with dissolved hydrogen, undesirably enrich waste slag and increase the proportion of metal in it. Properly performed process of melting non-ferrous metals and their proper further processing can reduce the occurrence of many defects, which are manifested on the castings in the form of porosity, depressions, oxide inclusions, and other side effects.