1. sulatusahju või koppa sisseviidav vedelat räbu moodustav materjal, mille ülesandeks on kahjulike lisandite eemaldamine sulametallist; 2. keevitusel ja jootmisel oksiidide jt ebasoovitavate ainete eemaldamine detailidelt, 1. in metal refining, a material added to a melt to remove undesirable substances, like sand, ash, or dirt; fluxing the melt facilitates the agglomeration and separation of such undesirable constituents from the melt; it is also used as a protective covering for certain molten metal baths; 2. in brazing, cutting, soldering, or welding, material used to prevent the formation of, or to dissolve and facilitate removal of, oxides and other undesirable substances