Fluxing involves the application of a special chemical coating onto the surface of the steel part. This “flux” serves the same purpose as fluxes used during soldering operations. The fluxing chemical (zinc ammonium chloride) is designed to chemically remove the last vestiges of oxides just as the steel is being immersed into the molten zinc, and allow the steel to be wetted by the molten zinc. Fluxing can be either “dry” or “wet”. Dry fluxing involves immersion of the steel part into an aqueous solution of the flux. Upon removal, the flux solution is dried prior to immersion into the zinc bath. (Note that there is a continuous galvanizing process that uses dry fluxing. It is described in GalvInfoNote 2.7). In wet fluxing, a blanket of liquid (molten) zinc ammonium chloride is floated on top of the molten zinc bath. The part to be coated is then immersed through the molten flux as it is being introduced into the coating bath. (Wet fluxing works because zinc ammonium chloride has a melting point below that of molten zinc and is less dense than molten zinc, thereby floating on the bath surface).
Fluxing - Fluxing is the final surface preparation step in the galvanizing process. Fluxing removes oxides and prevents further oxides from forming on the surface of the metal prior to galvanizing. The method for applying the flux depends upon whether the galvanizer uses the wet or dry galvanizing process.