<prompt> Casting flux is used toPrevent the oxidation of material during melting.Increase the melting point of the flux.Prevent the contamination of the metal and theliner.All of the above.  <response>: Fluxes are specifically usedTo remove gas or prevent its absorption into the melt.To reduce metal loss.To remove specific impurities and nonmetallic inclusionsTo refine metallic constituents, or to lubricate and control surface structure in the semi-continuous casting of metal alloys.Key conceptFlux powder may be sprinkled over the molten metal to reduce the oxides and increase fluidity for casting. 