Thanks to the mechanism of creation of the “filter cake” on the inlet filter side and thanks to depth filtration inside the ceramic matrix they represent the effective instrument enabling to reach metallurgical purity of the molten metal during the process of casting. The ceramic foam filters VUKOPOR® also calm mould filling, thus preventing creation of new inclusions and undesirable defects in the casting. The calming effect on mould filling is conditioned by conversion of turbulent liquid metal flow upstream the filter into the laminar flow downstream the filter.